全文获取类型
收费全文 | 8417篇 |
免费 | 888篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 75篇 |
儿科学 | 225篇 |
妇产科学 | 131篇 |
基础医学 | 1154篇 |
口腔科学 | 304篇 |
临床医学 | 968篇 |
内科学 | 1706篇 |
皮肤病学 | 110篇 |
神经病学 | 607篇 |
特种医学 | 311篇 |
外科学 | 1263篇 |
综合类 | 270篇 |
一般理论 | 6篇 |
预防医学 | 823篇 |
眼科学 | 202篇 |
药学 | 651篇 |
中国医学 | 1篇 |
肿瘤学 | 509篇 |
出版年
2021年 | 94篇 |
2020年 | 64篇 |
2019年 | 104篇 |
2018年 | 124篇 |
2017年 | 124篇 |
2016年 | 130篇 |
2015年 | 147篇 |
2014年 | 143篇 |
2013年 | 254篇 |
2012年 | 361篇 |
2011年 | 389篇 |
2010年 | 247篇 |
2009年 | 227篇 |
2008年 | 321篇 |
2007年 | 368篇 |
2006年 | 373篇 |
2005年 | 381篇 |
2004年 | 307篇 |
2003年 | 353篇 |
2002年 | 312篇 |
2001年 | 260篇 |
2000年 | 287篇 |
1999年 | 247篇 |
1998年 | 132篇 |
1997年 | 133篇 |
1996年 | 126篇 |
1995年 | 105篇 |
1994年 | 116篇 |
1993年 | 105篇 |
1992年 | 198篇 |
1991年 | 182篇 |
1990年 | 164篇 |
1989年 | 172篇 |
1988年 | 179篇 |
1987年 | 163篇 |
1986年 | 146篇 |
1985年 | 175篇 |
1984年 | 121篇 |
1983年 | 108篇 |
1982年 | 76篇 |
1981年 | 74篇 |
1980年 | 62篇 |
1979年 | 110篇 |
1978年 | 69篇 |
1977年 | 77篇 |
1976年 | 63篇 |
1973年 | 85篇 |
1972年 | 74篇 |
1971年 | 73篇 |
1970年 | 61篇 |
排序方式: 共有9316条查询结果,搜索用时 294 毫秒
1.
2.
3.
The MMPI was administered during the patient-perceived best time of the menstrual cycle and during the patient-perceived worst time of the cycle in order to examine the stability of MMPI profile configurations. Subjects were 214 women who were referred to two metropolitan outpatient premenstrual syndrome (PMS) clinics for moderate to severe premenstrual complaints. This sample was selected from 1,849 intake files after screening by strict selection criteria for PMS. The results indicate that there are wide fluctuations in profile patterns between the best and worst times of the menstrual cycle for a large number of patients. Caution in using the MMPI is strongly advised. 相似文献
4.
5.
Phase I study of high-dose cytosine arabinoside and etoposide in patients with advanced malignancies
Bayard L. Powell Hyman B. Muss Robert L. Capizzi Mary E. Caponera Douglas R. White Patricia J. Zekan James N. Atkins Don V. Jackson Jr. Frederick Richards II John B. Craig Julia M. Cruz Charles L. Spurr 《Cancer chemotherapy and pharmacology》1987,19(3):250-252
Summary Cytosine arabinsodie (ara-C) and etoposide (VP-16) display synergy in the laboratory. Twenty-six patients participated in a phase I study of high-dose ara-C in combination with VP-16. The dose of VP-16 was held constant at 50 mg/m2 as an intermittent infusion over 33 h; escalating doses of ara-C were given as infusions during hours 9–12 and 21–24. Myelosuppression was the dose-limiting toxicity and occurred with doses considerably less than those expected from studies of the two drugs as single agents. The suggested initial doses for phase II trials with this schedule are 750 mg/m2×2 doses of ara-C and 50 mg/m2 of VP-16. Nonhematologic toxicity was minimal; therefore, further dose escalation is feasible in patients in whom myelosuppression is acceptable.Supported in part by grants from the National Cancer Institute (CA-12197 and CA-09422) and the American Cancer Society CF-85-182 相似文献
6.
J E Richards A H Parmelee L Beckwith 《Electroencephalography and clinical neurophysiology》1986,64(1):1-11
Power spectral and discriminant analysis techniques were used to compare EEG records obtained at term and at 3 months past term from 5 groups of varying risk and developmental outcome. The groups were: healthy full-terms; healthy pre-terms with normal outcomes; sick pre-terms with normal outcomes; sick pre-terms with delayed development; sick pre-terms with later neurological problems. The EEG samples recorded at term were identified as belonging to the correct subject group at 52-70% accuracy, 20% being chance for 5 groups. The accuracy varied with the 4 classes of EEG patterns used. The individual subjects were also classified into their correct groups with few exceptions. Similar success was obtained with EEG samples selected from recording at 3 months past term. The predominant power spectral discriminating features were changes in intra- and inter-hemispheric coherence, and increased power, particularly in the middle and higher frequency range. Thus, computer analyses of EEG samples, using features not readily identified visually, differentiated risk from non-risk infants and also differentiated infants with substantial neonatal medical complications who have good or poor developmental outcomes. 相似文献
7.
D. Grant Richards Kevin G. Whithear Peter C. Scott Robin B. Gasser 《Acta parasitologica / Witold Stefański Institute of Parasitology, Warszawa, Poland》2006,51(2):156-159
Coccidiosis of chickens, caused by species of Eimeria (Protozoa, Apicomplexa), is an intestinal disease of major economic importance worldwide. In the present study, the reproductive
characteristics of a precocious line (designated E. tenella Rt3+15) from Australia were investigated in chicken embryos and the implications of the findings briefly discussed. 相似文献
8.
D. M. Richards N. Zhang S. L. Dalheimer D. L. Mueller 《American journal of transplantation》2007,7(10):2269-2278
To investigate the mechanism of CD4(+) T-cell help during the activation and differentiation of directly alloreactive CD8(+) T cells, we examined the development of obliterative airways disease (OAD) following transplantation of airways into fully mismatched recipient mice deficient in CD4(+) T cells. BALB/c trachea allografts became fibrosed significantly less frequently in B6 CD4(-/-) recipients as compared to wildtype controls. Furthermore, class I-directed cytotoxicity failed to develop in the absence of CD4(+) T cells. The infiltration of graft tissue by primed L(d)-specific directly alloreactive 2C CD8(+) T cells was not found to depend on the presence of CD4(+) T cells. Nevertheless, graft-infiltrating 2C CD8(+) T cells failed to express CD69 and granzyme B when CD4(+) T-cell help was unavailable. Importantly, reconstitution of B6 CD4(-/-) recipient mice with graft peptide-specific TCR-Tg CD4(+) T cells (OT-II or TEa) capable of recognizing antigen only on recipient APC allowed for full expression of CD69 and granzyme B by the directly alloreactive CD8(+) T cells and restored the capacity of recipients to reject their allografts. These results demonstrate that indirectly alloreactive CD4(+) T cells ensure the optimal activation and differentiation of graft-infiltrating directly alloreactive CD8(+) T cells independent of donor APC recognition. 相似文献
9.
E W Richards M Abu Khaled C L Watkins C L Long 《Nutrition (Burbank, Los Angeles County, Calif.)》1991,7(5):344-346
Nuclear magnetic resonance (NMR) spectroscopy has been reported as an alternative method for quantitating deuterium oxide concentrations in the evaluation of total-body-water in humans. However, the presence of dissolved plasma proteins results in an underestimation of deuterium NMR (2H-NMR) intensity ratios, thereby causing an overestimation (5-6%) of total-body-water (TBW) values determined from nonsublimed patient plasma samples. We demonstrate that plasma samples must be corrected for the volume percentage of water in plasma. Correction of initial 2H-NMR intensity ratios with a factor of 0.93 results in intensity ratios comparable to those determined from plasma samples subjected to vacuum sublimation to remove all plasma solutes. 相似文献
10.
J T Muldoon L A Wintermeyer J A Eure L Fuortes J A Merchant S F Van Lier T B Richards 《American journal of public health》1987,77(8):1006-1008
Health department epidemiologists in 50 states, New York City, and the District of Columbia were surveyed in 1985 about seven potential data sources for occupational disease surveillance. Reported sources of occupational disease data were: automated workers' compensation claims (63 per cent of the 52 respondents); provider reports (62 per cent); death certificates with occupation or industry (60 per cent); cancer registries with occupational histories (35 per cent); birth certificates with parent's occupation (27 per cent); non-cancer disease registries (13 per cent); and hospital or insurance records (8 per cent). 相似文献