全文获取类型
收费全文 | 971307篇 |
免费 | 101136篇 |
国内免费 | 1282篇 |
出版年
2018年 | 19400篇 |
2017年 | 18173篇 |
2016年 | 18044篇 |
2015年 | 15632篇 |
2014年 | 17591篇 |
2013年 | 24602篇 |
2012年 | 32083篇 |
2011年 | 41014篇 |
2010年 | 31468篇 |
2009年 | 26918篇 |
2008年 | 35506篇 |
2007年 | 37917篇 |
2006年 | 24373篇 |
2005年 | 24415篇 |
2004年 | 23894篇 |
2003年 | 23351篇 |
2002年 | 22269篇 |
2001年 | 37640篇 |
2000年 | 37888篇 |
1999年 | 30283篇 |
1998年 | 11662篇 |
1997年 | 12204篇 |
1996年 | 11635篇 |
1995年 | 10965篇 |
1994年 | 10783篇 |
1993年 | 10664篇 |
1992年 | 25360篇 |
1991年 | 24654篇 |
1990年 | 24305篇 |
1989年 | 23458篇 |
1988年 | 21670篇 |
1987年 | 21171篇 |
1986年 | 19463篇 |
1985年 | 19567篇 |
1984年 | 16298篇 |
1983年 | 14226篇 |
1982年 | 11278篇 |
1981年 | 10117篇 |
1980年 | 9601篇 |
1979年 | 15620篇 |
1978年 | 12553篇 |
1977年 | 11369篇 |
1976年 | 10714篇 |
1975年 | 11687篇 |
1974年 | 12583篇 |
1973年 | 12460篇 |
1972年 | 11627篇 |
1971年 | 10732篇 |
1970年 | 8845篇 |
1969年 | 8417篇 |
排序方式: 共有10000条查询结果,搜索用时 213 毫秒
741.
742.
743.
744.
WANG JC 《The Journal of general physiology》1948,31(3):259-268
1. Experiments were performed on six dogs to determine the rate of penetration of Cl(33) and Na(24) across the blood-aqueous humor and blood-cerebrospinal fluid barriers after intravenous injection of the radioactive ions. The radioactivity measurements were made with an immersion type of Geiger-Müller counter. 2. The concentrations of the labelled ions in the anterior chamber and the cisterna magna increase slowly to approach that of plasma. The rate of penetration k is calculated from a simple exponential equation with the half-value interval t(0.5) or the time required for the labelled-ion concentration in the fluid to reach 50 per cent of that of plasma. The average t(0.5) for Cl(38) and Na(24) in aqueous humor are 34.3 +/- 9 and 27.3 +/- 9 minutes, respectively, while those for cerebrospinal fluid are 90 +/- 6 and 95 +/- 6 minutes, respectively. 3. A study of the radioactivity in plasma was made to determine the per cent remaining after a steady state was reached. By means of this determination the sodium and chloride space was calculated to be 33 +/- 5 per cent. 相似文献
745.
746.
747.
C-Type Virus Released from Cultured Human Rhabdomyosarcoma Cells 总被引:44,自引:0,他引:44
R. M. McALLISTER M. NICOLSON M. B. GARDNER R. W. RONGEY S. RASHEED P. S. SARMA R. J. HUEBNER M. HATANAKA S. OROSZLAN R. V. GILDEN A. KABIGTING L. VERNON 《Nature: New biology》1972,235(53):3-6
RD-114 virus, released from human rhabdomyosarcoma cells, has all the characteristics of a mammalian C-type virus. Immunological tests indicate that it differs from all known C-type viruses and is the most likely candidate for a human C-type virus yet described. 相似文献
748.
749.
750.
The non-newtonian viscous and elasto-thixotropic properties of native and lyophilized pathological bronchial mucus and of polymer solutions (3% and 6% PIB in decalin) used as mucus analogs were analyzed using a cone-plate Carri-Med rheometer and a Couette viscoelastometer that we have specifically developed for measuring the rheological properties of bronchial mucus in clinical practice. The master curves obtained for apparent viscosity under steady conditions as a function of shear rates (gamma: 2.6 X 10(-3) to 6.9 X 10(1) sec-1) were fairly similar, whatever the apparatus used. Under transient conditions, at low shear rate (gamma less than 1.4 sec-1), PIB and mucus exhibited a typical viscoelastic behavior: the shear stress increased slightly up to a steady-state value. At higher gamma, a transitory overshoot of sigma characteristic of the elastothixotropic systems appeared. Such a behavior can be interpreted as resulting from structural changes such as formation and rupture of the three-dimensional network present in bronchial mucus as in polymer solutions. 相似文献