全文获取类型
收费全文 | 780064篇 |
免费 | 86731篇 |
国内免费 | 681篇 |
出版年
2018年 | 7438篇 |
2017年 | 7091篇 |
2016年 | 9921篇 |
2015年 | 13092篇 |
2014年 | 15440篇 |
2013年 | 22098篇 |
2012年 | 24914篇 |
2011年 | 25141篇 |
2010年 | 16995篇 |
2009年 | 15552篇 |
2008年 | 22034篇 |
2007年 | 22829篇 |
2006年 | 21393篇 |
2005年 | 20493篇 |
2004年 | 20054篇 |
2003年 | 19266篇 |
2002年 | 18773篇 |
2001年 | 39439篇 |
2000年 | 39598篇 |
1999年 | 30763篇 |
1998年 | 9849篇 |
1997年 | 10434篇 |
1996年 | 9850篇 |
1995年 | 9092篇 |
1994年 | 8836篇 |
1993年 | 8687篇 |
1992年 | 24841篇 |
1991年 | 23900篇 |
1990年 | 23066篇 |
1989年 | 22343篇 |
1988年 | 20607篇 |
1987年 | 19281篇 |
1986年 | 17817篇 |
1985年 | 17580篇 |
1984年 | 14368篇 |
1983年 | 12313篇 |
1982年 | 9161篇 |
1981年 | 8167篇 |
1980年 | 7716篇 |
1979年 | 13625篇 |
1978年 | 10353篇 |
1977年 | 9510篇 |
1976年 | 8635篇 |
1975年 | 9688篇 |
1974年 | 10365篇 |
1973年 | 10107篇 |
1972年 | 9275篇 |
1971年 | 8313篇 |
1970年 | 7265篇 |
1969年 | 6877篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
E. N. Medvedeva N. A. Neverova T. E. Fedorova V. A. Babkin E. S. Meteleva A. V. Dushkin T. G. Tolstikova M. V. Khvostov M. P. Dolgikh 《Russian Journal of Bioorganic Chemistry》2010,36(7):853-859
It has been found by gel-penetrating chromatography and quantitative 13C NMR spectroscopy that mechanochemical processing of arabinogalactan isolated from the wood of the Siberian larch changes
the molecular mass distribution, monosaccharide composition, and the degree of branching of its macromolecules. This is due
to the partial destruction of polysaccharide macromolecules and subsequent recombination of resulting fragments. The intensity
of these processes depends on the conditions of mechanochemical processing. Based on the data of IR and 13C NMR spectra, the conclusion has been drawn that no functionalization of arabinogalactan macromolecules occurs under these
conditions. The toxicopharmacological properties of mechanically processed arabinogalactan have been studied. Its acute toxicity
is >5000 mg/kg. 相似文献
92.
93.
V K Khugaeva E D Klimenko P N Aleksandrov G F Leskova M I Reutov 《Biulleten' eksperimental'no? biologii i meditsiny》1985,100(7):15-19
Experiments were made on rabbit fed an atherogenic diet (0.5 g/kg cholesterol) singly for 15 and 24 h and repeatedly for 3, 9 and 30 days. At early stages of lipid metabolism distress the interrelationship was established between blood rheological disorders and microcirculatory abnormalities. The dependence of the initial reaction of some rheological characteristics on their initial level was marked. 相似文献
94.
95.
M A Pass M W Goosem S Pollitt 《Comp. Biochem. Physiol. C, Comp. Pharmacol. Toxicol.》1985,82(2):457-461
The metabolism of the cholestatic triterpene acid reduced lantadene A has been studied in susceptible and resistant rats and in sheep which are susceptible to intoxication. Sheep and susceptible female rats produced a similar major metabolite and rats produced a second metabolite which was a glucuronide. These metabolites were also observed in extracts of bile canalicular membranes prepared from intoxicated rats. Resistant male and female rats produced a similar major metabolite which was different to those synthesized by susceptible animals. It is concluded that in rats and sheep there is a correlation between the type of metabolites produced in the liver and the susceptibility to intoxication by reduced lantadene A. 相似文献
96.
Transport of chloride across cell membranes through exchange, cotransport, or conductive pathways is a subject of great biological importance. Current methods of measurement are restricted in their sensitivity, time resolution, and applicability. A new transport measurement technique has been developed on the basis of the fluorescence quenching by chloride of the dye 6-methoxy-N-(3-sulfopropyl)quinolinium (SPQ). SPQ fluorescence quenching by chloride is rapid (less than 1 ms) and sensitive, with a greater than 50% decrease in fluorescence at 10 mM chloride. SPQ fluorescence is not altered by other physiological anions or by pH and can be used to measure both neutral and conductive transport processes. The high water solubility and membrane permeability properties of SPQ make it ideal for use in both membrane vesicles and cells. Chloride transport determined with SPQ was validated by measurement of erythrocyte chloride/anion exchange and membrane vesicle chloride conductance. 相似文献
97.
Purification and characterization of a membrane-bound protein kinase from spinach thylakoids 总被引:3,自引:0,他引:3
A protein kinase was isolated from spinach thylakoid membranes by solubilization with octyl glucoside and cholate. The enzyme was purified to apparent homogeneity by ammonium sulfate precipitation, gel filtration, and sucrose density centrifugation, followed by affinity chromatography on either Affi-Gel blue (yielding denatured enzyme) or on histone cross-linked to Sepharose (yielding active enzyme). Electrophoresis on denaturing polyacrylamide gels, followed by staining with silver, revealed the kinase as a single band corresponding to an apparent molecular mass of 64 kDa. The active enzyme underwent autophosphorylation and could be detected by autoradiography following incubation with [gamma-32P]ATP and Mg2+ ion. The specific phosphotransferase activity of purified kinase was approximately 30 nmol of phosphate min-1 (mg protein)-1 with lysine-rich histone (III-S or V-S) as substrate; casein was phosphorylated at approximately 30% of this rate. The physiological substrate for the kinase is presumed to be light-harvesting chlorophyll a/b protein complex. In solubilized form, this was phosphorylated at approximately 10% of the rate observed with histone III-S as substrate, or 10-100 times slower than the estimated rate of phosphorylation of the light-harvesting complex in situ. Possible reasons for this shortfall are considered. The kinase is proposed as the principal effector of thylakoid protein phosphorylation and associated State transition phenomena. 相似文献
98.
99.
100.
EEG activity was recorded in rats submitted to osmotic opening of the BBB by intracarotid mannitol infusion.This procedure produced an immediate short-lasting depression of the EEG and a tardive paroxysmal EEG activity. Both these phenomena were more relevant on the ipsilateral hemisphere. In some instances a tonico-clonic seizure was recorded.Pre-treatment with diazepam abolished the occurrence of the tardive EEG and behavioral modifications.In accord with previous findings, focal seizure activity is likely to be responsible for the metabolic abnormalities associated with osmotic opening of the BBB. This preparation therefore produces in the brain unphysiological states in respect to local metabolism and electrical function. 相似文献