全文获取类型
收费全文 | 529828篇 |
免费 | 47469篇 |
国内免费 | 265篇 |
出版年
2018年 | 9754篇 |
2017年 | 9375篇 |
2016年 | 9437篇 |
2015年 | 7091篇 |
2014年 | 8778篇 |
2013年 | 12361篇 |
2012年 | 15989篇 |
2011年 | 20443篇 |
2010年 | 14508篇 |
2009年 | 13643篇 |
2008年 | 17881篇 |
2007年 | 19644篇 |
2006年 | 13407篇 |
2005年 | 13229篇 |
2004年 | 13162篇 |
2003年 | 13014篇 |
2002年 | 12886篇 |
2001年 | 24879篇 |
2000年 | 24987篇 |
1999年 | 19094篇 |
1998年 | 5684篇 |
1997年 | 5868篇 |
1996年 | 5429篇 |
1995年 | 4931篇 |
1994年 | 4873篇 |
1993年 | 4909篇 |
1992年 | 15040篇 |
1991年 | 15129篇 |
1990年 | 14629篇 |
1989年 | 14435篇 |
1988年 | 13420篇 |
1987年 | 12562篇 |
1986年 | 11407篇 |
1985年 | 11448篇 |
1984年 | 9069篇 |
1983年 | 7736篇 |
1982年 | 5393篇 |
1981年 | 4711篇 |
1980年 | 4559篇 |
1979年 | 8299篇 |
1978年 | 6405篇 |
1977年 | 5832篇 |
1976年 | 5403篇 |
1975年 | 6316篇 |
1974年 | 6760篇 |
1973年 | 6630篇 |
1972年 | 6451篇 |
1971年 | 6014篇 |
1970年 | 4829篇 |
1969年 | 4684篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Sign language studies of cross-fostered chimpanzees measure the effect of special rearing conditions on the development of
very young chimpanzees. Cross-fostered chimpanzees, like human children, develop gradually in a process that takes many years.
Here we discuss details of the procedure, the overlap between human and chimpanzee infants in the contents of the first 50-item
vocabularies, and the ways in which the signs of the chimpanzees exhibit the fuzziness of natural language categories. We
also compare the cross-fostering approach with more traditional modular approaches to the study of language-like behavior
in nonhuman animals.
Project Washoe was originally supported by grants MH-12154 from the National Institute of Mental Health and GB-7432 from the
National Science Foundation. We gratefully acknowledge this support and the support that later sign language studies of chimpanzees
have received since then from NIH, NSF, the National Geographic Society, the Grant Foundation, the Spencer Foundation, the
University of Nevada, and the UNR Foundation. 相似文献
992.
993.
R C Strange B T Chapman J D Johnston I A Nimmo I W Percy-Robb 《Biochimica et biophysica acta》1979,573(3):535-545
1. The subcellular distribution of conjugates of cholic acid and chenodeoxycholic acid between cytosol, nuclei, mitochondria and microsomes in rat liver has been determined. 2. The partition coefficients for the distribution of these bile acids between subcellular fractions and buffer have been measured and used to construct a compartmental model of the amounts of conjugated bile acids present in the different subcellular organelles in vivo. 3. This model indicates that a large percentage of the bile acid in the rat liver is found in the nuclear fraction; 42% of the cholic acid conjugates and 27% of the chenodeoxycholic acid conjugates. Substantial amounts of bile acid are also present in microsomes and mitochondria suggesting that published estimates of the amounts of bile acids in these fractions are underestimates. 4. The model also allows the amount of bile acid which is in free solution in cytosol to be determined; 10.9% of the cholic acid conjugates and 4.1% of the chenodeoxycholic acid conjugates in rat liver were present in this fraction. Knowlege of the amount of free bile acid allows possible roles of the cytosolic bile binding proteins to be assessed. 相似文献
994.
J A T Dyer 《BMJ (Clinical research ed.)》1980,281(6250):1277-1278
995.
A non-blue copper-containing glycoprotein was isolated from Pseudomonas aeruginosa. The protein has a molecular mass of 10 kDa and contains 1 atom of EPR-detectable type II copper. The protein inhibits oxidation of both azurin and cytochrome c-551 catalyzed by nitrite reductase from Ps. aeruginosa. Thus, it may be considered as an endogenous inhibitor of nitrite reductase. 相似文献
996.
Iu V Burov S N Orekhov N N Vedernikova 《Biulleten' eksperimental'no? biologii i meditsiny》1986,101(4):442-444
The effect of different chemical anxiolytic agents on ethanol consumption has been studied on the model of experimental alcoholism in rats. The decrease of ethanol consumption was dose-dependent. The existence of non-benzodiazepine anxiolytic systems is suggested. 相似文献
997.
M Nishioka T Aibiki M Shirai S Terada H Kagawa S Watanabe 《Microbiology and immunology》1986,30(12):1291-1297
Actin is a major antigen involved in the reaction of smooth muscle antibody positive sera from patients with chronic active hepatitis. In the present study, actin extracted from rabbit skeletal muscle was denatured by sodium dodecyl sulfate and was immunized into the rabbit, a homologous animal for actin. The rabbits, thus immunized, produced antibodies reactive with actins of homologous and heterologous animals. In addition, the antibodies showed reactivity with autologous actin. It indicates that the denatured homologous actin is capable of terminating immunological tolerance to actin and induces formation of autoantibody to rabbit actin. This phenomenon may be implicated in the occurrence of anti-actin antibody in sera from patients with chronic liver disease and several other diseases. 相似文献
998.
G N Kryzhanovski? N G Lutsenko V N Grafova E I Danilova V K Lutsenko 《Biulleten' eksperimental'no? biologii i meditsiny》1986,101(4):399-401
The ability of serotonin derivatives to stimulate cAMP accumulation in isolated nerve terminals and lumbar enlargement of the spinal cord of normal rats was compared. The effect of the compounds on the intensity of spinal pain syndrome was also assessed. It has been established that substitutes injected into NH2-group of serotonin in 5-OH position attenuate the ability to stimulate cAMP accumulation in synaptosomes, with the effect more pronounced with substitutes of larger volume. A certain correlation between the ability of serotonin derivatives to stimulate adenylate cyclase in vivo and in vitro, on the one hand, and their analgetic effect, on the other hand, is suggested. 相似文献
999.
It was demonstrated that the nuclear matrix of rat liver possesses the protease activity. The specific activity of nuclear matrix proteases exceeds that of intact nuclei 7-fold. The optimum activity of nuclear matrix proteases is observed at pH 8-9. The protease activity of the nuclear matrix is inhibited by p-chloromercuribenzoate, N-ethylmaleimide, EDTA, phenylmethylsulfonyl fluoride. This suggests that thiol, serine and metalloproteases are associated with the nuclear matrix. 相似文献
1000.
I E Ganelina L M Kukui J P Nikolaewa T E Schumilowa W E Cholmogorow K W Timofeew A L Schurigin 《Folia haematologica (Leipzig, Germany : 1928)》1982,109(3):470-482
We observed 70 male patients with a seriously proceeding Chronic myocardial ischemia. They were hospitalised because of frequent, permanent and serious attacks of stenocardia at rest and in stress situations. More than 2/3 of these patients had suffered from a myocardial infarct. In the course of two weeks an intensive therapy with all modern preparations for vasodilatation was made. This therapy proved to be unsuccessful. Nearly all patients were administered more than 10 tables of nitroglycerin per day and, in addition, they were injected analgetics as a compensation of attack. The ultraviolet own blood irradiation (UVB) had a positive therapeutic effect in all patients. There was a good success in 46 patients, in all patients satisfactory results could be registered. The effect of therapy was evident by the decrease of administration of nitroglycerin required, by an increase in the degree of stress capacity, and by an easier treatment of stenocardia attacks. The observation time for patients amounted to 2-8 months. The success of therapy remained in 38 patients. After this time the success of therapy could partially be regained by a repeated number of irradiation series. Then, it remained positive in 9 of 22 patients who had been followed-up for 10 months. The half decay period of eliminating 131I from an intradermal depot could be normalised under the influence of ultraviolet own blood irradiation. This ultraviolet own blood irradiation had no significant influence on the fibrinogen level, fibrinolytic activity, and erythrocyte aggregation (examined in 11 patients). A 2 1/2-fold diminution of monomer fibrin complexes in the blood could be observed. The titre of antistreptolysin-O was increased in all patients who had got over the infarct. It had completely normalised a week after finishing the ultraviolet own blood irradiation. Spectroscopic examinations of the blood and plasma made after ultraviolet own blood irradiation revealed that this irradiation will not only affect the properties of Hb, but will also cause a photochemical transformation accompanied by a destruction of some plasma proteins, of the membrane of formed blood elements, and a photosynthesis of biochemically active compounds. The mechanism of action of ultraviolet own blood irradiation is complicated and requires further exact investigations. Even today, however, this method can be recommended as a complex therapy in patients with severe myocardial ischemia. 相似文献