全文获取类型
收费全文 | 2282篇 |
免费 | 238篇 |
国内免费 | 1篇 |
出版年
2023年 | 12篇 |
2022年 | 28篇 |
2021年 | 45篇 |
2020年 | 39篇 |
2019年 | 50篇 |
2018年 | 50篇 |
2017年 | 58篇 |
2016年 | 78篇 |
2015年 | 116篇 |
2014年 | 127篇 |
2013年 | 141篇 |
2012年 | 179篇 |
2011年 | 175篇 |
2010年 | 122篇 |
2009年 | 76篇 |
2008年 | 130篇 |
2007年 | 148篇 |
2006年 | 97篇 |
2005年 | 95篇 |
2004年 | 92篇 |
2003年 | 108篇 |
2002年 | 74篇 |
2001年 | 55篇 |
2000年 | 48篇 |
1999年 | 34篇 |
1998年 | 16篇 |
1997年 | 12篇 |
1996年 | 17篇 |
1995年 | 10篇 |
1994年 | 12篇 |
1993年 | 14篇 |
1992年 | 27篇 |
1991年 | 16篇 |
1990年 | 17篇 |
1989年 | 11篇 |
1988年 | 15篇 |
1987年 | 19篇 |
1986年 | 18篇 |
1985年 | 27篇 |
1984年 | 15篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 5篇 |
1979年 | 11篇 |
1978年 | 8篇 |
1975年 | 6篇 |
1972年 | 8篇 |
1971年 | 4篇 |
1970年 | 6篇 |
排序方式: 共有2521条查询结果,搜索用时 15 毫秒
11.
Richard B. Marchase Vincent J. Kidd Angel A. Rivera Michael G. Humphreys-Beher 《Journal of cellular biochemistry》1988,36(4):453-465
Rat parotid gland acinar cells stimulated to divide by a chronic regimen of isoproterenol demonstrate a dramatic increase in the synthesis of the glycosyltransferase 4β-galactosyltransferase. A plasma membrane localization for much of the increase in 4β-galactosyltransferase was determined by density gradient membrane fractionation. Golgi-enriched fractions showed no increase in specific activity, while plasma membrane activity increased 40-fold. This selective increase at the cell surface was confirmed by immunofluorescence of intact, nonpermeabilized cells from treated glands, using a monospecific antibody prepared against the purified bovine milk transferase. In detergent-permeabilized cells staining of nontreated cells was seen only as groups of perinuclear vesicles, presumed to be Golgi apparatus. In isoproterenol-treated and permcabilized cells both presumptive Golgi and cell surface staining was apparent. Enzyme assays performed on intact cells established that the enzyme's active site was oriented to the exterior of the cells. The transferase could be detected as early as 3 hr after the primary challenge with isoproterenol. Pretrcatment of rats with cycloheximide prevented its appearance. 相似文献
12.
Giuseppe Ravizzola Gabriele Pinsi Marina Cesana Carmela De Rango Laura Peroni Prof. Adolfo Turano 《Current microbiology》1992,24(6):349-353
The protective effects of rufloxacin againstStaphylococcus aureus-induced infections were compared with those of ciprofloxacin in the granuloma pouch model in the rat. Two strains with different in vitro sensitivity to the drugs were studied. Rufloxacin concentrations persisted longer than ciprofloxacin in the exudate in the pouch cavity and were about eight times higher. Equal doses of rufloxacin and ciprofloxacin had similar antibacterial activities. However, rufloxacin inhibitedStaphylococcus aureus bacterial growth significantly longer than did ciprofloxacin. 相似文献
13.
14.
H Rivera M Moller L M Baltazar A Escalante-Herrera D Garcia-Cruz 《Annales de génétique》1988,31(4):244-246
A 24-year-old female with a Swyer syndrome phenotype was found to have a 46,X,del (Y) (p11) karyotype. This observation is consistent with the recently confirmed assignment of the testis-determining master gene to the deletion interval 1A of the Y (Page et al., 1987). Otherwise, it illustrates the etiological heterogeneity of the Swyer phenotype and allows to emphasize the de novo origin of XYp-females. 相似文献
15.
Isolation of fecal coliforms from pristine sites in a tropical rain forest. 总被引:6,自引:4,他引:2 下载免费PDF全文
Samples collected from water accumulated in leaf axilae of bromeliads (epiphytic flora) in a tropical rain forest were found to harbor fecal coliforms. Random identification of fecal coliform-positive isolates demonstrated the presence of Escherichia coli. This bacterium was also isolated from bromeliad leaf surfaces. These data indicate that E. coli may be part of the phyllosphere microflora and not simply a transient bacterium of this habitat. The isolation of fecal coliforms from these sites was unexpected and raises questions as to the validity of using fecal coliforms as indicators of biological water quality in the tropics. 相似文献
16.
Rogelio O. Arellano Fidel Ramón Amelia Rivera Guido A. Zampighi 《The Journal of membrane biology》1986,94(3):293-299
Summary The effect of pH was tested on the junction between crayfish lateral axons. By means of a glass capillary inserted into one of the axons, one side of the nunction was perfused with solutions of known pH while the junctional resistance,R
j, was monitored. Integrity of the gap junction was checked electron microscopically.R
j remained unchanged when the pH of the perfusate was lowered from 7.1 to 6.0. However, when the pH of the unperfused side of the junction was lowered by substituting acetate for chloride in the external solution,R
j rose, attesting to the integrity of the junction and its capacity to uncouple in the perfused state. We suggest that H+ does not affect the junctional channels directly, but acts through an intermediary which is inactivated or removed by the perfusion. 相似文献
17.
F Rivas D García-Cruz H Rivera M L Plascencia R M González J M Cantú 《Annales de génétique》1985,28(2):113-115
A 2 4/12-year-old girl whith a de novo 46,XX,-22 + der(22), t(19;22)(q13.2;p11) karyotype is described. From this and other eight similar cases previously published, a typical phenotype in distal 19q trisomy is concluded. 相似文献
18.
M T Sole-Pujol H Rivera L P Castro-Felix M Moller J M Cantu 《Journal de génétique humaine》1985,33(1):57-62
A hitherto undescribed inv(2) (p2300q11.2) was found in 2 generations of a family ascertained through a holoprosencephalic liveborn boy with normal karyotype. This inversion, quite probably not related to the child malformations, does not seem neither impair reproductive fitness nor to yield viable recombination aneusomies. 相似文献
19.
Jerome Harold Kay Harold K. Tsuji John V. Redington Yasunaru Kawashima Yuzuru Kagawa Takashi Yamada Peter Caponegro Adolfo Mendez 《The Western journal of medicine》1967,106(3):165-169
A disc valve of new design was used successfully for the replacement of the mitral valve in patients with rheumatic mitral valve disease. This valve would appear to have the following advantages over the mitral ball valve prosthesis:• Lower left atrial pressure after replacement.• Elimination of the hazard of left ventricular outflow tract obstruction with mitral valve replacement.• Decreased incidence of thromboembolization.• Abolition of possibility of ventricular septal irritation.Despite the better outlook for this valve compared with the ball valve for mitral valve substitution, the mitral valve should always be repaired whenever feasible. Repair is possible in the majority of patients. 相似文献
20.