全文获取类型
收费全文 | 12709篇 |
免费 | 1026篇 |
国内免费 | 74篇 |
专业分类
耳鼻咽喉 | 75篇 |
儿科学 | 326篇 |
妇产科学 | 200篇 |
基础医学 | 1575篇 |
口腔科学 | 229篇 |
临床医学 | 1668篇 |
内科学 | 2455篇 |
皮肤病学 | 165篇 |
神经病学 | 1258篇 |
特种医学 | 650篇 |
外国民族医学 | 1篇 |
外科学 | 2035篇 |
综合类 | 225篇 |
现状与发展 | 1篇 |
一般理论 | 9篇 |
预防医学 | 1016篇 |
眼科学 | 226篇 |
药学 | 926篇 |
中国医学 | 48篇 |
肿瘤学 | 721篇 |
出版年
2023年 | 52篇 |
2021年 | 225篇 |
2020年 | 137篇 |
2019年 | 203篇 |
2018年 | 275篇 |
2017年 | 198篇 |
2016年 | 209篇 |
2015年 | 228篇 |
2014年 | 384篇 |
2013年 | 477篇 |
2012年 | 744篇 |
2011年 | 903篇 |
2010年 | 433篇 |
2009年 | 443篇 |
2008年 | 673篇 |
2007年 | 804篇 |
2006年 | 654篇 |
2005年 | 745篇 |
2004年 | 622篇 |
2003年 | 619篇 |
2002年 | 604篇 |
2001年 | 237篇 |
2000年 | 267篇 |
1999年 | 262篇 |
1998年 | 205篇 |
1997年 | 175篇 |
1996年 | 150篇 |
1995年 | 124篇 |
1994年 | 131篇 |
1993年 | 122篇 |
1992年 | 161篇 |
1991年 | 143篇 |
1990年 | 143篇 |
1989年 | 155篇 |
1988年 | 144篇 |
1987年 | 145篇 |
1986年 | 129篇 |
1985年 | 157篇 |
1984年 | 133篇 |
1983年 | 98篇 |
1982年 | 89篇 |
1981年 | 108篇 |
1980年 | 75篇 |
1979年 | 84篇 |
1978年 | 73篇 |
1977年 | 75篇 |
1976年 | 67篇 |
1975年 | 42篇 |
1974年 | 46篇 |
1972年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
91.
P67L: a cystic fibrosis allele with mild effects found at high frequency in the Scottish population. 下载免费PDF全文
A Gilfillan J P Warner J M Kirk T Marshall A Greening L P Ho T Hargreave B Stack D McIntyre R Davidson J C Dean W Middleton D J Brock 《Journal of medical genetics》1998,35(2):122-125
Only three mutant cystic fibrosis (CF) alleles have to date been established as conferring a dominant mild effect on affected subjects who are compound heterozygotes. We now add a fourth, P67L, which occurs on about 1.4% of Scottish CF chromosomes. Among 13 patients (12 unrelated) with this allele, the average age at diagnosis was 22.5 +/- 11.3 years. None of the cases had consistently raised sweat chloride concentrations, the average value being 57 +/- 9 mmol/l; 77% of the patients were pancreatic sufficient. When compared to three other established mild CF alleles, R117H, A455E, and 3849 + 10kb C-T, a compound heterozygote for P67L has minimal disease and clinical suspicions are unlikely to be confirmed other than by DNA typing. 相似文献
92.
Jeffrey W. Gray Arlene I. Rattan Raymond S. Dean 《Archives of clinical neuropsychology》1986,1(4):341-349
This study examined the utility of the Halstead-Reitan Neuropsychological Battery in the differential diagnosis of dementia, major depression, and general neurological impairment. Orthogonal contrasts between groups showed superior performance for depressives on most Halstead-Reitan subtests. Contrasts between organically impaired groups showed that these groups did not differ significantly (p >.05) on any of the Halstead-Reitan subtests. A step-wise discriminant analysis indicated that on the basis of neuropsychological variables alone, demented patients were differentiated from elderly depressed with clinical levels of accuracy. However, when neurologically impaired and demented patients were considered together in a single group reflecting organic impairment, hits increased dramatically. The results were discussed in terms of their implications for differentially diagnosing dementia and depression in the elderly. 相似文献
93.
Quantitative study of the immunoglobulin-containing cells in trephine samples of bone marrow 下载免费PDF全文
Immunoglobulin (Ig) was demonstrated in paraffin sections of 12 trephine bone marrow biopsies by means of the unlabelled antibody peroxidase-antiperoxidase (PAP) method. The Ig-containing cells, which were counted with the Reichert-Jung (Kontron) MOP-AMO3 user-controlled image-analyser, were found to constitute approximately 4·2% of all the nucleated cells in the marrow, a figure significantly higher than those reported by previous workers. 相似文献
94.
A preparative method to remove dihydroxy-terminated components in a sample of presumably monomethoxy, monohydroxy-terminated poly(ethylene glycol) (PEG) is presented. Purification of the monomethoxy-terminated component allows one to prepare a diblock copolymer of PEG and poly(lactic acid) (PLLA) free of a PLLA-PEG-PLLA triblock copolymer in various biomedical applications of the copolymer. Efficiency of the purification is compared for high osmotic pressure chromatography (HOPC) and preparative size exclusion chromatography (SEC). In HOPC, various types of porous silica particles, surfaces, solvents, polymer concentrations have been screened for the optimal performance. It was found that HOPC is more efficient than SEC, especially HOPC of 30-40 wt% solutions in water by a column packed with acid-washed controlled pore glass is optimal in producing high-purity fractions. 相似文献
95.
96.
Hirsh A.V.; Mills C.; Bekir J.; Dean N.; Yovich J.L.; Tan S.L. 《Human reproduction (Oxford, England)》1994,9(9):1710-1716
Microsurgical epididymal sperm aspiration (MESA) and in-vitrofertilization (IVF) were found to offer limited opportunityfor fatherhood to 45 men with obstructive azoospermia, due principallyto poor embryo implantation. Adequate sperm preparations wereobtained in 46/50 treatment cycles (92%), with the best motilityfound in the caput epididymis in 89% of cases. The mean fertilizationrate was 11.2% and fertilization occurred in 23 cycles (50%),with embryo transfer arising from 12/26 men with was aplasia(CAV), 4/9 with genital tract obstruction (EV) and 7/11 withirreversible vasectomy (VV). The overall implantation rate waslow, 8.7% per embryo transfer (11.7% per 2-3 embryo transfers)and was not improved by Fallopian transfer. There were two pregnancies(4% per cycle), both in the EV group where embryo formationand implatation (2/4, 50% per cycle) were optimum even thoughsperm preparations were paradoxically inferior to the CAV andVV groups. The spermatozoa retrieved in the two successful EVcycles were appreciably blood contaminated. Analysis of the21 failed embryo transfers showed delayed fertilization in 10cycles, cystic fibrosis (CF) mutation or familial disease in7/12 CAV men and the VV men were older (P<0.001). A pregnancywhich miscarried arose from a case of Young's syndrome, a carrierof CF mutation DF508. Male factors could thus be implicatedin the high embryo wastage of MESA cycles and might also beinfluencing implantation in other IVF procedures. Where feasible,male reconstructive surgery is preferable unless fertilizationcan be improved, possibly by speedier retrieval techniques orby permitting sperm capacitation in vitro, but probably moreeffectively by micro-assisted insemination. 相似文献
97.
Construct validity of the PPVT with neuropsychological, intellectual, and achievement measures 总被引:2,自引:0,他引:2
The present investigation examined the construct validity of the Peabody Picture Vocabulary Test (PPVT) with learning-disabled children. The Wechsler Intelligence Scale for Children-Revised (WISC-R), the Wide Range Achievement Test, and the Halstead-Reitan Neuropsychological Battery were administered to 934 learning-disabled children. Seven factors were isolated on the basis of a principal-components factor analysis and Varimax rotation. PPVT scores were found to load on a factor similar to what has been labeled verbal comprehension on the WISC-R with little secondary loadings on any of the remaining six factors. Implications for practitioners and further research were discussed. 相似文献
98.
Dean K Whitla Gary Orfield William Silen Carole Teperow Carolyn Howard Joan Reede 《Academic medicine》2003,78(5):460-466
PURPOSE: Many U.S. medical schools have abandoned affirmative action, limiting the recruitment and reducing the admission of underrepresented minority (URM) students even though research supports the premise that the public benefits from an increase in URM physicians and that URM physicians are likely to serve minority, poor, and Medicaid populations. Faculty and students commonly assume they benefit from peer cultural exchange, and the published evidence for the past two decades supports this notion. This research examined the students' perceptions of the educational merits of a diverse student body by surveying medical students at two schools. METHOD: In 2000, medical students from all four years at Harvard Medical School and the University of California, San Francisco, School of Medicine were enrolled in a telephone survey about the relevance of racial diversity (among students) in their medical education. Students responded to the interviewer's questions on a five-point Likert-type scale. RESULTS: Of the 55% of students who could be located, 97% responded to the survey. Students reported having little intercultural contact during their formative years but significantly more interactions during higher education years, especially in medical school. Students reported contacts with diverse peers greatly enhanced their educational experience. They strongly supported strengthening or maintaining current affirmative action policies in admissions. The responses and demography of the Harvard and UCSF students did not differ significantly, nor did they differ for majority students and URM students-all groups overwhelmingly thought that racial and ethnic diversity among their peers enhanced their education. CONCLUSIONS: Diversity in the student body enhanced the educational experiences of students in two U.S. medical schools. 相似文献
99.
The increased rate of Ca2+ uptake and ATPase activity in isolated cardiac sarcoplasmic reticulum (SR) by adenosine 3,5-monophosphate (cAMP) has been shown to be activated by a cAMP-dependent protein kinase (cAMP kinase). Functionally skinned myocardial fiber preparations were used to study the mechanisms of cAMP action on the SR at the same time that tension was monitored. cAMP effects were studied on Ca2+-activated tension of the contractile proteins, and on Ca2+ uptake and release from the SR using caffeine-induced tension transients. Neither cyclic AMP (0.1–5 M) nor the catalytic subunit of cAMP kinase (0.1–1 M) (PK-C) significantly changed either the maximal or the submaximal Ca2+-activated tension. The areas of the tension transients were unchanged when cAMP was present in the releasing solution (release phase), and were significantly increased up to a mean of about 80% when cAMP or PK-C was present in the Ca2+ loading solutions (uptake phase). The increased tension transient was blocked by the heat-stable inhibitor of cAMP kinase. We conclude that cAMP-induced increases in Ca2+ uptake by the SR could play an important role in the positive inotropic effect. cAMP kinase could thus play a crucial role in the regulation of myocardial contractility. 相似文献
100.
N. B. Ruderman H. Park V. K. Kaushik D. Dean S. Constant M. Prentki A. K. Saha 《Acta physiologica (Oxford, England)》2003,178(4):435-442
An increasing body of evidence has revealed that activation of adenosine monophosphate (AMP)‐activated protein kinase (AMPK)‐activated protein kinase increases fatty acid oxidation by lowering the concentration of malonyl coenzyme A (CoA), an inhibitor of carnitine palmitoyl transferase 1. Studies carried out primarily in skeletal muscle suggest that AMPK modulates the concentration of malonyl CoA by concurrently phosphorylating and inhibiting acetyl CoA carboxylase (ACC), the rate limiting enzyme in malonyl CoA synthesis, and phosphorylating and activating malonyl CoA decarboxylase (MCD), an enzyme involved in its degradation. We have recently observed that AMPK and MCD activities are increased and ACC activity diminished in skeletal muscle, liver and, surprisingly, in adipose tissue 30 min following exercise (treadmill run) in normal rats. In liver and adipose tissue these changes were associated with a decrease in the activity of glycerol‐3‐phosphate acyltransferase (GPAT), which catalyses the first committed reaction in glycerolipid synthesis and, which like ACC, is phosphorylated and inhibited by AMPK. Similar changes in ACC, MCD and GPAT were observed following the administration of 5‐aminoimidazole 4‐carboxamide‐riboside (AICAR), further indicating that the exercise‐induced alterations in these enzymes were AMPK‐mediated. Conclusions: (1) AMPK plays a major role in regulating lipid metabolism in multiple tissues following exercise. (2) The net effect of its activation is to increase fatty acid oxidation and diminish glycerolipid synthesis. (3) The relevance of these findings to the regulation of muscle glycogen repletion in the post‐exercise state and to the demonstrated ability of AMPK activation to decrease adiposity and increase insulin sensitivity in rodents remains to be determined. 相似文献