However, drugs delivered directly to the CSF do not effectively penetrate into the brain tissue itself, possibly due to the tortuous nature of the interstitial space in the brain.

However, this exchange is not direct but instead is effected through an intermediary called interstitial fluid or tissue fluid that the blood forms.

However, it reacts with molten metals, hydrogen, halogens, chalcogens and pnictogens to form various binary compounds.

However, today the IUPAC system of chemical nomenclature allows chemists to specify by name specific compounds amongst the vast variety of possible chemicals.

However, not all substances or chemical compounds consist of discrete molecules, and indeed most of the solid substances that makes up the solid crust, mantle, and core of the Earth are chemical compounds without molecules.

However, in principle, since the same electronegativities should be obtained for any two bonding compounds, the data is in fact overdetermined, and the signs are unique once a reference point is fixed ( usually, for H or F ).

However, gas chromatography testing in 1984 revealed that sulfur-containing compounds, such as methanethiol, hydrogen sulfide ( rotten egg smell ) and dimethyl sulfide, were also < ref >

However, synthetic soluble germanium salts are nephrotoxic, and synthetic chemically reactive germanium compounds with halogens and hydrogen are irritants and toxins.

However, chelated Gd ( III ) compounds are far less toxic because they carry Gd ( III ) through the kidneys and out of the body before the free ion can be released into tissue.

However, some ionic compounds can conduct electricity when solid.

However, an indefinitely larger number of such compounds are theoretically possible.

However, this cannot be said of present-day Mandarin, in which most words are compounds ( around 80 %), and most roots are bound.

However, as is the case on Earth, nitrogen and its compounds occur commonly as gases in the atmospheres of planets and moons that have atmospheres.

However, radiocarbon dating can often be used on the inks that make up the writing, since many of them contain organic compounds such as plant leachings, soot, and wine.

However, not all organisms that use light as a source of energy carry out photosynthesis, since photoheterotrophs use organic compounds, rather than carbon dioxide, as a source of carbon.

However, having four bonding electrons gives it, like carbon, many opportunities to combine with other elements or compounds under the right circumstances.

For example, all salts of sodium, potassium and ammonium are soluble in water, as are all nitrates and many sulfate salts except barium sulfate, calcium sulfate ( sparingly soluble ) and Lead ( 2 ) sulfate However, ions that bind tightly to each other and form highly stable lattices would be less soluble, because it would be harder for these structures to break apart for the compounds to dissolve.

However, most gases and some compounds exhibit solubilities that decrease with increased temperature.

However, like the other lanthanides, the most common oxidation state is + 3, seen in its oxide, halides and other compounds.

However, they occasionally have a Chinese on reading, derived from a phonetic, as in 働, dō, from 動, and in rare cases only have an on reading, as in 腺, sen, from 泉, which was derived for use in technical compounds ( 腺 means " gland ", hence used in medical terminology ).

However, although these substances have been used throughout history by various cultures, and have a profound effect on mentality and brain function, they have not always attained the degree of scrutinous evaluation that lab-made compounds have.

However, resins consist primarily of secondary metabolites or compounds that apparently play no role in the primary physiology of a plant.

However many tire compounds contain enough carbon black to provide an electrical ground which prevents charge build-up.

However, other preparation methods such as steaming, microwaving, and stir frying had no significant effect on the compounds.

However, many of these compounds have already an established trivial name, which is endorsed by the IUPAC nomenclature, for example chloroform ( trichloromethane ) and methylene chloride ( dichloromethane ).

However, several iron-based compounds ( the iron pnictides ) are now known to be superconducting at high temperatures.

However, in recent decades, for what doubtless are multiple reasons, an unannounced but nonetheless readily observable shift has occurred in both facets of national activity.

However, in the context of legal and civic policy, these controversies are less than novel.

However, despite the insight of many of his observations, his own conclusions are open to suspicion because of his failure to employ at all times the correct research methods.

However, there are still several types of calls that necessitate the use of telephone operators.

However, he states unequivocally `` the scandals in business are far less significant than the scandals in labor ''.

However, few are taxed, and the owners and location of most boats are unknown to the assessors on the date of assessment of town valuations.

However, the surface temperature gradient can produce erroneous vapor-pressure measurements for the bulk liquid helium unless precautions are taken to isolate the tube ( which passes through the surface to the vapor pressure bulb ) from the liquid helium surface.

However, if their United States income is not subject to the withholding of tax on wages, their returns are due June 15, 1962, if they use a calendar year, or the 15th day of the 6th month after the close of their fiscal year.

However, the aircraft which we have today are tied to large, `` soft '' airfields.

However, some formulas are used more than others.

However, there is also much to be gained by making use of the abilities of the local people who are available and interested in recreation.

However, there are photographs of suspended drops of cyclohexanol phthalate ( viscosity 155 poises ) suspended in corn syrup of 71 poises in a paper by Mason and Bartok.

However, any oxygen nonequivalence would shorten either the already extremely short Af interlayer distance of 2.55 A or the non-hydrogen-bonded Af interlayer interactions which are already quite short at 2.58 Aj.

However, as so many of the records are not certainly based on newborn snakes, these data must be taken tentatively ; ;

However, if these procedures are applied more often, conditioned emotional responses are temporarily abolished.

However, it cannot be presumed, informal though the structure of the population seems, that there are not well-defined roles within the system.

However, the differences in procedure are fundamental.

However, the regionally differentiated results, which appear below in tables, are interesting evidence of the problems of developing self-government under even the most favorable circumstances.

However, if Federal funds are used, it would be entirely appropriate to train workers for jobs which could be obtained elsewhere as well as for jobs in the area of chronic unemployment.

However, it is not known to either the union or the public precisely how much of a cost increase is caused by a given change in the basic wage rate, although the companies are presumed to have reliable estimates of this magnitude.

However, there are relatively few such political constituencies, and, as has been pointed out, there is seldom a clear-cut distinction between the educational interests of one social class and those of another.

However, modesty and triviality are different qualities.

`` However, evidence that the Axis powers are making significant preparations indicative of such an intention is being reported with increasing frequency from a variety of sources.