全文获取类型
收费全文 | 3823篇 |
免费 | 238篇 |
国内免费 | 26篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 228篇 |
妇产科学 | 69篇 |
基础医学 | 471篇 |
口腔科学 | 115篇 |
临床医学 | 384篇 |
内科学 | 893篇 |
皮肤病学 | 62篇 |
神经病学 | 214篇 |
特种医学 | 530篇 |
外科学 | 300篇 |
综合类 | 41篇 |
一般理论 | 1篇 |
预防医学 | 241篇 |
眼科学 | 38篇 |
药学 | 213篇 |
中国医学 | 11篇 |
肿瘤学 | 261篇 |
出版年
2023年 | 12篇 |
2022年 | 49篇 |
2021年 | 75篇 |
2020年 | 38篇 |
2019年 | 73篇 |
2018年 | 89篇 |
2017年 | 57篇 |
2016年 | 62篇 |
2015年 | 78篇 |
2014年 | 101篇 |
2013年 | 158篇 |
2012年 | 122篇 |
2011年 | 132篇 |
2010年 | 135篇 |
2009年 | 118篇 |
2008年 | 156篇 |
2007年 | 132篇 |
2006年 | 137篇 |
2005年 | 129篇 |
2004年 | 102篇 |
2003年 | 103篇 |
2002年 | 82篇 |
2001年 | 79篇 |
2000年 | 96篇 |
1999年 | 86篇 |
1998年 | 155篇 |
1997年 | 129篇 |
1996年 | 151篇 |
1995年 | 102篇 |
1994年 | 86篇 |
1993年 | 92篇 |
1992年 | 47篇 |
1991年 | 62篇 |
1990年 | 40篇 |
1989年 | 91篇 |
1988年 | 73篇 |
1987年 | 79篇 |
1986年 | 78篇 |
1985年 | 72篇 |
1984年 | 42篇 |
1983年 | 48篇 |
1982年 | 42篇 |
1981年 | 29篇 |
1980年 | 47篇 |
1979年 | 25篇 |
1978年 | 24篇 |
1977年 | 23篇 |
1976年 | 32篇 |
1975年 | 27篇 |
1965年 | 11篇 |
排序方式: 共有4087条查询结果,搜索用时 0 毫秒
11.
We report an adult female with a rare giant choledochal cyst. The patient presented following a normal pregnancy with the classical triad of an abdominal mass associated with jaundice and right upper quadrant abdominal pain. The cyst was excised using an intramural technique and biliary reconstruction achieved with a Roux-en-Y hepaticojejunostomy. Our patient has remained well with no evidence of malignancy over a 12 year review period. The aetiology and current management of this condition are discussed. 相似文献
12.
M I Arrieta B Criado B Martinez A Simon L Salazar C M Lostao 《Annals of human biology》1991,18(3):221-233
Digital dermatoglyphics of a sample from the Basque Valley of Salazar, situated in the West of the Pyrenees, were analysed. The results showed bimanual differences in both sexes, and also sexual differences for both hands. The comparative study with other Basque valleys showed that, in spite of their supposed common origin, the geographic barriers and the isolation have generated a genetic/dermatoglyphic and linguistic differentiation. 相似文献
13.
14.
From 1969 through 1977, 210 patients with Stage IB carcinoma of the uterine cervix were treated at University of Maryland Hospital. Fifty-six patients were treated by radical hysterectomy (S), 136 patients were treated by a full course of radiation therapy (RT) only and 18 patients received radiation treatment following radical surgery (S + RT). The 5-year determinate survival rates were almost the same in the S group and RT alone group (79% and 77%, respectively). The 5-year determinate survival rate in the S + RT group was 50%, which was statistical significantly lower than S alone or RT alone groups (P less than 0.05). Several prognostic factors were analyzed in the radiated patients: the size of the primary lesion, location of the lesion within the cervix, tumor grade, age of the patients at the time of diagnosis, and complete blood count nadir during the course of radiation treatment. The only factor found to influence the prognosis was the size of the primary tumor. The patients with smaller tumors had a better prognosis; the absolute and determinate 5-year survival rates were 80% and 82%, while the absolute and determinate survival rates in the large, fungating tumor replacing the entire cervix were 56% and 60%, respectively (P less than 0.001). The complication rate was 22% in the RT alone, 22% in the S + RT, and 25% in the S alone groups. 相似文献
15.
Laska M Fendt M Wieser A Endres T Hernandez Salazar LT Apfelbach R 《Physiology & behavior》2005,84(2):211-215
2,4,5-trimethylthiazoline (TMT) is a volatile component of the anal gland secretion of the red fox and elicits behavioral and physiological fear responses in the rat. Using instrumental conditioning paradigms, we determined olfactory detection thresholds for TMT in three rats, a natural prey species of the red fox, and compared their performance to that of three squirrel monkeys, three spider monkeys and four pigtail macaques, all non-prey species of the red fox. We found that the rats were able to discriminate concentrations between 0.04 and 0.10 ppt (parts per trillion) of TMT from the odorless solvent which is by far the lowest olfactory detection threshold for an odorant reported in rats so far. In contrast, the spider monkeys needed 0.14-1.38 ppb (parts per billion), the pigtail macaques 0.41-4.07 ppb, and the squirrel monkeys 4.07-13.80 ppb to detect TMT which does not rank among the lowest olfactory thresholds reported for these three primate species. Thus, these results support the assumption that the behavioral relevance of an odorant may be an important determinant of a species' olfactory sensitivity. 相似文献
16.
Na+ dependence of in vitro pancreatic amylase release 总被引:1,自引:0,他引:1
17.
Responses to natural scenes in cat V1 总被引:3,自引:0,他引:3
Studies on processing in primary visual areas often use artificial stimuli such as bars or gratings. As a result, little is known about the properties of activity patterns for the natural stimuli processed by the visual system on a daily basis. Furthermore, in the cat, a well-studied model system for visual processing, most results are obtained from anesthetized subjects and little is known about neuronal activations in the alert animal. Addressing these issues, we measure local field potentials (lfp) and multiunit spikes in the primary visual cortex of awake cats. We compare changes in the lfp power spectra and multiunit firing rates for natural movies, movies with modified spatio-temporal correlations as well as gratings. The activity patterns elicited by drifting gratings are qualitatively and quantitatively different from those elicited by natural stimuli and this difference arises from both spatial as well as temporal properties of the stimuli. Furthermore, both local field potentials and multiunit firing rates are most sensitive to the second-order statistics of the stimuli and not to their higher-order properties. Finally, responses to natural movies show a large variability over time because of activity fluctuations induced by rapid stimulus motion. We show that these fluctuations are not dependent on the detailed spatial properties of the stimuli but depend on their temporal jitter. These fluctuations are important characteristics of visual activity under natural conditions and impose limitations on the readout of possible differences in mean activity levels. 相似文献
18.
Determination of optimal cryoprotectants and procedures for their addition and removal from human spermatozoa 总被引:9,自引:7,他引:9
The objective was to test the hypothesis that the optimal cryoprotective
agent for cryopreservation of human spermatozoa would be a solute for which
cells have the highest plasma membrane permeability, resulting in the least
amount of volume excursion during its addition and removal. To test this
hypothesis, theoretical simulations were performed using membrane
permeability coefficients to predict optimal procedures for the addition
and removal of a cryoprotectant. Simulations were performed using data from
four different cryoprotectants: (i) glycerol, (ii) dimethyl sulphoxide,
(iii) propylene glycol and (iv) ethylene glycol. Thermodynamic formulations
were applied to determine approaches for the addition and removal of 1 M
and 2 M final concentrations of cryoprotectant, allowing the spermatozoa to
maintain a cell volume within their osmotic tolerance limits. Based on
these data, ethylene glycol was predicted to be optimal for minimizing
volume excursions among the solutes evaluated. These predictions were then
experimentally tested using glycerol as the control cryoprotectant and
ethylene glycol as the experimental cryoprotectant. The results indicate
that there was a higher (P < 0.05) recovery of motile spermatozoa after
cryopreservation when using 1 M ethylene glycol than with 1 M glycerol,
supporting the hypothesis that use of the cryoprotectant for which the cell
has the highest permeability will result in higher cell survival.
相似文献
19.
Salazar MR 《Medical hypotheses》2000,55(6):510-512
Insulin resistance has been associated with people diagnosed with depression. Conversely, it has also been documented that diabetics have an increased risk of depression. Evidence suggests that insulin activity plays a role in serotonergic activity by increasing the influx of tryptophan into the brain. This increased influx of tryptophan has been shown to result in an increase in serotonin synthesis. In accordance with the serotonin theory of depression, it may be possible to treat depression by increasing insulin activity. The antioxidant alpha lipoic acid has been shown to increase insulin sensitivity and is used to treat people with diabetes. Therefore, the nutrient alpha lipoic acid should be clinically tested as an adjunct treatment for depression. 相似文献
20.
Expression of P-cadherin identifies prostate-specific-antigen-negative cells in epithelial tissues of male sexual accessory organs and in prostatic carcinomas. Implications for prostate cancer biology. 总被引:1,自引:0,他引:1 下载免费PDF全文
A. P. Soler G. D. Harner K. A. Knudsen F. X. McBrearty E. Grujic H. Salazar A. C. Han A. A. Keshgegian 《The American journal of pathology》1997,151(2):471-478
Cadherins constitute a family of calcium-dependent cell-cell adhesion molecules the individual members of which are essential for the sorting of cells into tissues during development. In this study, we examined the expression of E-cadherin, N-cadherin, and P-cadherin in tissues obtained from radical prostatectomies. Epithelial cells of prostatic glands, ejaculatory ducts, and seminal vesicles expressed E-cadherin but not N-cadherin. P-cadherin was expressed in epithelial cells of the seminal vesicles and ejaculatory ducts. In the prostate it was limited to the basal cells of prostatic acini, glands with basal cell hyperplasia, and atrophic glands denuded of the luminal cells. All P-cadherin-positive cells were negative for prostatic-specific antigen. Prostatic cancers were mostly P-cadherin negative, but some tumors had P-cadherin-positive areas frequently located close to ejaculatory ducts and negative for prostatic-specific antigen. The mutually exclusive expression of P-cadherin and prostatic-specific antigen suggests that these proteins are involved in differential mechanisms of cell regulation in prostate cancer. P-cadherin may become a useful marker in the diagnosis and management of patients with prostate cancer and low levels of prostatic-specific antigen. 相似文献