全文获取类型
收费全文 | 14154篇 |
免费 | 1251篇 |
国内免费 | 10篇 |
出版年
2023年 | 45篇 |
2021年 | 238篇 |
2020年 | 150篇 |
2019年 | 195篇 |
2018年 | 219篇 |
2017年 | 187篇 |
2016年 | 347篇 |
2015年 | 598篇 |
2014年 | 617篇 |
2013年 | 840篇 |
2012年 | 1008篇 |
2011年 | 1019篇 |
2010年 | 658篇 |
2009年 | 581篇 |
2008年 | 868篇 |
2007年 | 901篇 |
2006年 | 811篇 |
2005年 | 781篇 |
2004年 | 789篇 |
2003年 | 738篇 |
2002年 | 692篇 |
2001年 | 162篇 |
2000年 | 108篇 |
1999年 | 165篇 |
1998年 | 174篇 |
1997年 | 131篇 |
1996年 | 120篇 |
1995年 | 111篇 |
1994年 | 100篇 |
1993年 | 114篇 |
1992年 | 113篇 |
1991年 | 82篇 |
1990年 | 95篇 |
1989年 | 68篇 |
1988年 | 85篇 |
1987年 | 87篇 |
1986年 | 72篇 |
1985年 | 96篇 |
1984年 | 90篇 |
1983年 | 91篇 |
1982年 | 108篇 |
1981年 | 99篇 |
1980年 | 91篇 |
1979年 | 61篇 |
1978年 | 60篇 |
1977年 | 54篇 |
1976年 | 60篇 |
1975年 | 48篇 |
1974年 | 52篇 |
1973年 | 64篇 |
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
11.
Anthony J. Hesketh Caroline Maloney Christopher A. Behr Morris C. Edelman Richard D. Glick Yousef Al-Abed Marc Symons Samuel Z. Soffer Bettie M. Steinberg 《PloS one》2015,10(12)
Metastatic Ewing Sarcoma carries a poor prognosis, and novel therapeutics to prevent and treat metastatic disease are greatly needed. Recent evidence demonstrates that tumor-associated macrophages in Ewing Sarcoma are associated with more advanced disease. While some macrophage phenotypes (M1) exhibit anti-tumor activity, distinct phenotypes (M2) may contribute to malignant progression and metastasis. In this study, we show that M2 macrophages promote Ewing Sarcoma invasion and extravasation, pointing to a potential target of anti-metastatic therapy. CNI-1493 is a selective inhibitor of macrophage function and has shown to be safe in clinical trials as an anti-inflammatory agent. In a xenograft mouse model of metastatic Ewing Sarcoma, CNI-1493 treatment dramatically reduces metastatic tumor burden. Furthermore, metastases in treated animals have a less invasive morphology. We show in vitro that CNI-1493 decreases M2-stimulated Ewing Sarcoma tumor cell invasion and extravasation, offering a functional mechanism through which CNI-1493 attenuates metastasis. These data indicate that CNI-1493 may be a safe and effective adjuvant agent for the prevention and treatment of metastatic Ewing Sarcoma. 相似文献
12.
Alexis L. Moore Joseph E. Budny Anthony P. Russell Michael T. Butcher 《Journal of morphology》2013,274(1):35-48
Evaluation of the relationships between muscle structure and digging function in fossorial species is limited. Badgers and other fossorial specialists are expected to have massive forelimb muscles with long fascicles capable of substantial shortening for high power and applying high out‐force to the substrate. To explore this hypothesis, we quantified muscle architecture in the thoracic limb of the American badger (Taxidea taxus) and estimated the force, power, and joint torque of its intrinsic musculature in relation to the use of scratch‐digging behavior. Architectural properties measured were muscle mass, belly length, fascicle length, pennation angle, and physiological cross‐sectional area. Badgers possess hypertrophied shoulder flexors/humeral retractors, elbow extensors, and digital flexors. The triceps brachii is particularly massive and has long fascicles with little pennation, muscle architecture consistent with substantial shortening capability, and high power. A unique feature of badgers is that, in addition to elbow joint extension, two biarticular heads (long and medial) of the triceps are capable of applying high torques to the shoulder joint to facilitate retraction of the forelimb throughout the power stroke. The massive and complex digital flexors show relatively greater pennation and shorter fascicle lengths than the triceps brachii, as well as compartmentalization of muscle heads to accentuate both force production and range of shortening during flexion of the carpus and digits. Muscles of most functional groups exhibit some degree of specialization for high force production and are important for stabilizing the shoulder, elbow, and carpal joints against high limb forces generated during powerful digging motions. Overall, our findings support the hypothesis and indicate that forelimb muscle architecture is consistent with specializations for scratch‐digging. Quantified muscle properties in the American badger serve as a comparator to evaluate the range of diversity in muscle structure and contractile function that exists in mammals specialized for fossorial habits. J. Morphol. 2013. © 2012 Wiley Periodicals, Inc. 相似文献
13.
Timothy J. French Anthony W. Good T. Norman Palmer Mary C. Sugden 《Bioscience reports》1985,5(9):729-734
The in vivo effects of dexamethasone administration on liver and extrahepatic tissue carnitine concentrations were assessed in 48-h-starved rats. In heart and kidney, but not in liver, dexamethasone significantly increased total carnitine concentration. Acute (2.5 h) treatment with 2-tetradecylglycidate (TDG), a specific inhibitor of carnitine palmitoyl transferase 1, not only increased total hepatic carnitine concentrations, but also permitted an effect of dexamethasone (a further increase in hepatic carnitine concentration). The results are discussed in terms of acute (substrate-mediated) and chronic (hormonal) control of carnitine turnover. 相似文献
14.
Anthony D Redmond 《BMJ (Clinical research ed.)》2005,330(7502):1259-1261
15.
16.
17.
18.
19.
Peter W. Wilson Katie E. Osterday Aaron F. Heneghan Anthony D. J. Haymet 《The Journal of biological chemistry》2010,285(45):34741-34745
In this study, we examined the effects that antifreeze proteins have on the supercooling and ice-nucleating abilities of aqueous solutions. Very little information on such nucleation currently exists. Using an automated lag time apparatus and a new analysis, we show several dilution series of Type I antifreeze proteins. Our results indicate that, above a concentration of ∼8 mg/ml, ice nucleation is enhanced rather than hindered. We discuss this unexpected result and present a new hypothesis outlining three components of polar fish blood that we believe affect its solution properties in certain situations. 相似文献
20.