全文获取类型
收费全文 | 450426篇 |
免费 | 55758篇 |
国内免费 | 283篇 |
专业分类
506467篇 |
出版年
2018年 | 3839篇 |
2017年 | 3518篇 |
2016年 | 5478篇 |
2015年 | 8208篇 |
2014年 | 9217篇 |
2013年 | 12926篇 |
2012年 | 14908篇 |
2011年 | 15016篇 |
2010年 | 9898篇 |
2009年 | 9174篇 |
2008年 | 13100篇 |
2007年 | 13600篇 |
2006年 | 12285篇 |
2005年 | 12098篇 |
2004年 | 11873篇 |
2003年 | 11292篇 |
2002年 | 10795篇 |
2001年 | 21668篇 |
2000年 | 21801篇 |
1999年 | 17430篇 |
1998年 | 6243篇 |
1997年 | 6502篇 |
1996年 | 6320篇 |
1995年 | 5724篇 |
1994年 | 5765篇 |
1993年 | 5592篇 |
1992年 | 13668篇 |
1991年 | 12977篇 |
1990年 | 12666篇 |
1989年 | 12524篇 |
1988年 | 11189篇 |
1987年 | 10807篇 |
1986年 | 9907篇 |
1985年 | 9676篇 |
1984年 | 8210篇 |
1983年 | 7078篇 |
1982年 | 5532篇 |
1981年 | 5017篇 |
1980年 | 4659篇 |
1979年 | 7715篇 |
1978年 | 5936篇 |
1977年 | 5440篇 |
1976年 | 5080篇 |
1975年 | 5381篇 |
1974年 | 5832篇 |
1973年 | 5668篇 |
1972年 | 5106篇 |
1971年 | 4730篇 |
1970年 | 3922篇 |
1969年 | 3852篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
995.
996.
S. C. Rai 《Biometrical journal. Biometrische Zeitschrift》1987,29(4):449-454
A multi-sample slippage test based on ordered observations has been given. The test statistic is based on the sum of ranks of the sample. The probability distribution of the test statistic has been worked out for small sample and it turns out to be chi-square distribution for large sample. The analytical procedure has been explained by a numerical example. 相似文献
997.
We describe the use of a suprahyoid flap for reconstruction in the lower anterior neck. It has been most useful for immediately closing pharyngostomes and for resurfacing defects from the excision of squamous cell carcinoma of the larynx or other neoplasms involving the skin. This flap provides a good deal of viable tissue, it can easily be rotated without a delay procedure, and the donor area is closed by direct suture. We present our experience with 22 cases. 相似文献
998.
The cat hindlimb contains several long, biarticular strap muscles composed of parallel muscle fascicles that attach to short tendons. Three of these muscles--sartorius, tenuissimus, and semitendinosus--were studied by dissecting individual gold-stained fibers and determining the surface distribution of acetylcholinesterase-stained end-plate zones. In each muscle, fascicles were composed of muscle fibers that ran only part of the fascicle length and tapered to end as fine strands that interdigitated with other tapering fibers within the muscle mass. Most muscle fibers measured 2-3 cm in length. Fascicles of muscle fibers were crossed by short transverse bands of endplates (1 mm wide by 1-5 mm long) that were spaced at fairly regular intervals from the origin to the insertion of the muscle. The endplate pattern suggested that the fiber fascicles were organized into multiple longitudinal strips. In the sartorius, the temporospatial distribution of electromyographic (EMG) activity evoked by stimulating fine, longitudinal branches of the parent nerve confirmed that each strip was selectively innervated by a small subset of the motor axons. These axons appeared to distribute their endings throughout the entire length of the fascicles, providing for synchronous activation of their in-series fibers. 相似文献
999.
Elliott C. Kulakowski Joseph Maturo Stephen W. Schaffer 《Archives of biochemistry and biophysics》1981,210(1):204-209
Cardiac sarcolemma preparations of both pig and rat ventricles were found to possess two sets of taurine-binding components. The two proteins from pig heart were solubilized with the detergent Ammonyx-Lo. Characterization of these solubilized proteins revealed that both components are glycoproteins and retain the binding properties observed for the membrane isolate. However, the characterization also revealed several differences between the proteins including their binding specificities, their affinities for taurine, their binding isotherms, and their molecular sizes. Possible functions of these two taurine-binding proteins are discussed. 相似文献
1000.
Respiratory gas exchange and incorporation of 14C-leucine intoprotein were studied in proximal root segments from 25-day-oldmaize plants grown for the last ten days in 50 mM Na2SO4. 14C-leucineincorporation, and oxygen uptake in the presence of glucose,were as large in Na2SO4-grown tissues tested under saline conditionsas in tissues exposed to non-saline solutions throughout Thisadaptation was attributed to an increased metabolic capacityof Na2SO4-treated tissues, because these tissues, when returnedto non-saline solutions, evolved oxygen and incorporated 14C-leucinefaster than tissues exposed continuously to non-saline solutions. These changes are interpreted as a compensationfor the inhibitory effects found when non-adapted tissues wereexposed to 50 mM Na2SO4. Moreover, we have related them to ultrastructuralchanges observed previously in xylem parenchyma cells of thesetissues, and to the possible involvement of these xylem parenchymacells in the re-absorption of sodium from the ascending xylemfluid Zea mays L., maize, salt-stress, respiration, protein synthesis 相似文献