全文获取类型
收费全文 | 8961篇 |
免费 | 2487篇 |
国内免费 | 127篇 |
专业分类
耳鼻咽喉 | 370篇 |
儿科学 | 191篇 |
妇产科学 | 251篇 |
基础医学 | 192篇 |
口腔科学 | 151篇 |
临床医学 | 2884篇 |
内科学 | 1659篇 |
皮肤病学 | 307篇 |
神经病学 | 684篇 |
特种医学 | 329篇 |
外科学 | 1293篇 |
综合类 | 360篇 |
现状与发展 | 2篇 |
预防医学 | 1700篇 |
眼科学 | 100篇 |
药学 | 198篇 |
1篇 | |
中国医学 | 100篇 |
肿瘤学 | 803篇 |
出版年
2024年 | 62篇 |
2023年 | 410篇 |
2022年 | 115篇 |
2021年 | 257篇 |
2020年 | 486篇 |
2019年 | 166篇 |
2018年 | 557篇 |
2017年 | 599篇 |
2016年 | 615篇 |
2015年 | 707篇 |
2014年 | 706篇 |
2013年 | 1035篇 |
2012年 | 381篇 |
2011年 | 329篇 |
2010年 | 510篇 |
2009年 | 627篇 |
2008年 | 300篇 |
2007年 | 231篇 |
2006年 | 270篇 |
2005年 | 187篇 |
2004年 | 144篇 |
2003年 | 109篇 |
2002年 | 106篇 |
2001年 | 178篇 |
2000年 | 111篇 |
1999年 | 149篇 |
1998年 | 269篇 |
1997年 | 285篇 |
1996年 | 308篇 |
1995年 | 243篇 |
1994年 | 173篇 |
1993年 | 117篇 |
1992年 | 85篇 |
1991年 | 81篇 |
1990年 | 73篇 |
1989年 | 92篇 |
1988年 | 70篇 |
1987年 | 56篇 |
1986年 | 49篇 |
1985年 | 52篇 |
1984年 | 45篇 |
1983年 | 43篇 |
1982年 | 30篇 |
1981年 | 44篇 |
1980年 | 19篇 |
1979年 | 10篇 |
1978年 | 13篇 |
1977年 | 15篇 |
1976年 | 14篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Tai-Chan Peng MD Robert P. Kusy PhD Philip F. Hirsch PhD John R. Hagaman BA 《Alcoholism, clinical and experimental research》1988,12(5):655-659
Chronic ingestion of ethanol resulted in ultrastructural and mechanical changes in rat femurs. Scanning electron microscopy of the distal end of the femur revealed that the trabeculae of bones from ethanol-fed rats were thinner, more columnar, and more extensive than those from control rats. Three-point bending tests of the rat femurs showed that the maximum force or so-called "strength" required to break the bone was less in ethanol- than in control-fed animals. A significant inverse correlation was observed between the strength required to break the femur and the dose of ethanol calculated on a body weight basis. For the first time our study presents quantitative proof that a relationship exists between bone strength and the consumption of ethanol in rats. The study revealed that ethanol consumption resulted in a weaker femur compared to controls. We suggest that a common mechanism may be responsible for the decreased bone strength of ethanol-fed rats and the increased incidence of fractures in human alcoholics. 相似文献
92.
Summary The effects of personality characteristics on social support and hence risk of depression are explored in a group of 150 largely working-class mothers, a subsample of 400 women who took part in a prospective study. This established that once those with depression at first interview were excluded, practically all of the onsets of depression in the follow-up year occurred among 150 women with a severe event or major difficulty — that is a provoking agent. It was also found that low self-esteem and lack of support from a core tie at the time of the crisis was associated with a considerably increased risk. In the subsample as a whole, measures of dependency and attitudinal constraints to support taken at first interview were not associated with risk of depression. But, it is argued, any enduring personality traits that play a role in the link between lack of support and depression would most likely be seen in a smaller group, namely those who had had early inadequate parenting. And the most promising lead concerning the role of personality characteristics did in fact emerge in relation to a small high risk group with such parenting. Most of them had low self-esteem, and they appeared to confide in inappropriate and unreliable sources of support at time of crisis. 相似文献
93.
The effects of co-culture with human fibroblasts on human embryo development in vitro and implantation 总被引:5,自引:0,他引:5
Wetzels AM; Bastiaans BA; Hendriks JC; Goverde HJ; Punt-van der Zalm AP; Verbeet JG; Braat DD 《Human reproduction (Oxford, England)》1998,13(5):1325-1330
In a human in-vitro fertilization (IVF) programme, the effect of co-
culture of embryos with human fibroblasts was evaluated with respect to
pregnancy rate and embryo development. Patients were included in the study
after giving informed written consent. The IVF treatments were randomly
assigned by stratification of both age (<36 versus > or =36 years)
and previous IVF attempts (yes versus no). After fertilization was
established, the zygotes were transferred to a 4-well dish with or without
fibroblasts and cultured for 2 days. On the third day after ovum pick-up
(OPU), cell number and quality [5 (good) to 1 (poor)] of the embryos were
scored and a maximum of three embryos was transferred. Supernumerary
embryos of good quality were cryopreserved. The design of this study was a
group sequential trial with the objective of detecting differences between
pregnancy rates following IVF with conventional incubation or incubation in
co-culture with fibroblasts. This design included one evaluation at
half-way data collection. In the study, 148 patients had an OPU, of whom 77
were allocated to the co-culture group. There was no statistically
significant difference in pregnancy rate, cell number and embryo quality
between the two groups. The ongoing pregnancy rate per embryo transfer was
27% in co-culture and 30% in the conventional culture group. The
implantation rates per transferred embryo were 17 and 18% respectively.
Using a multivariate logistic regression model for the probability of
ongoing pregnancies, the odds ratio of co-culture, adjusted for age and
previous IVF attempts, was not statistically significant. In conclusion,
co-culture with human fibroblasts does not contribute to an improvement of
embryo quality nor to a higher pregnancy rate after IVF in an unselected
group of patients.
相似文献
94.
Hydrosalpinges adversely affect markers of endometrial receptivity 总被引:22,自引:10,他引:22
Meyer WR; Castelbaum AJ; Somkuti S; Sagoskin AW; Doyle M; Harris JE; Lessey BA 《Human reproduction (Oxford, England)》1997,12(7):1393-1398
While in-vitro fertilization (IVF) was initially developed in women with
tubal factor infertility, recent clinical studies have suggested that the
presence of hydrosalpinges lowers implantation and pregnancy rates. We
postulated that these hydrosalpinges cause impaired endometrial
receptivity. A total of 103 women with hydrosalpinges were prospectively
evaluated, and compared with 55 infertile and 44 fertile controls. All
women had endometrial biopsies during the window of implantation, analysed
by conventional histological criteria, and also stained for three integrin
markers of endometrial receptivity (alpha1beta1, alpha4beta1 and alpha
vbeta3). Women with hydrosalpinges (cases) expressed significantly less of
the alpha vbeta3 integrin compared with controls. There was no difference
in expression of alpha1beta1 or alpha4beta1 among groups. A significantly
greater number of cases had out of phase histology and missing alpha vbeta3
(type I defects) and absent integrin expression despite normal histological
maturation (type II) defects, compared with controls. Of 20 women with
impaired endometrial receptivity who were also biopsied after hydrosalpinx
surgery, 70% demonstrated increased alpha vbeta3 expression. Seventy-seven
percent of type I and 57% of type II defects were corrected
postoperatively. Using markers of endometrial receptivity, this study
demonstrates that inflammatory hydrosalpinges have an adverse effect on
endometrial receptivity, which in some cases may be overcome by surgical
treatment of the hydrosalpinx.
相似文献
95.
96.
Sequence comparison of human and yeast telomeres identifies structurally distinct subtelomeric domains 总被引:6,自引:2,他引:6
Flint J; Bates GP; Clark K; Dorman A; Willingham D; Roe BA; Micklem G; Higgs DR; Louis EJ 《Human molecular genetics》1997,6(8):1305-1313
We have sequenced and compared DNA from the ends of three human
chromosomes: 4p, 16p and 22q. In all cases the pro-terminal regions are
subdivided by degenerate (TTAGGG)n repeats into distal and proximal sub-
domains with entirely different patterns of homology to other chromosome
ends. The distal regions contain numerous, short (<2 kb) segments of
interrupted homology to many other human telomeric regions. The proximal
regions show much longer (approximately 10-40 kb) uninterrupted homology to
a few chromosome ends. A comparison of all yeast subtelomeric regions
indicates that they too are subdivided by degenerate TTAGGG repeats into
distal and proximal sub-domains with similarly different patterns of
identity to other non-homologous chromosome ends. Sequence comparisons
indicate that the distal and proximal sub-domains do not interact with each
other and that they interact quite differently with the corresponding
regions on other, non- homologous, chromosomes. These findings suggest that
the degenerate TTAGGG repeats identify a previously unrecognized,
evolutionarily conserved boundary between remarkably different subtelomeric
domains.
相似文献
97.
Brianne C. Miller MPH Aaron J. Goldenberg PhD MA MPH Natasha F. Bonhomme BA 《American journal of medical genetics. Part C, Seminars in medical genetics》2021,187(1):64-69
Parents use the internet to connect with their peers and access information about a multitude of health topics, including newborn screening (NBS). As the NBS system evolves, education about NBS must be evaluated and updated to remain accessible and beneficial to parents. In this article, we aim to describe parents' current NBS educational needs and highlight areas to improve newborn screening education by detailing an analysis of NBS posts on an online parenting discussion platform. We analyzed a total of 317 discussion posts on BabyCenter®, finding that parents had questions about and desired support around many aspects of NBS including processes, results, and follow‐up. As a result of this analysis, three recommendations to improve NBS education were developed. Through collaboration and by leveraging technology, we can provide parents with accessible, timely, and desired NBS informational and social support. 相似文献
98.
Horne G; Jamaludin A; Critchlow JD; Falconer DA; Newman MC; Oghoetuoma J; Pease EH; Lieberman BA 《Human reproduction (Oxford, England)》1998,13(11):3045-3048
Insemination with donor spermatozoa is an integral part of infertility
treatment. For the last 3 years in our unit, intrauterine insemination with
donor spermatozoa (IUID) has been used in preference to vaginal
insemination. In this retrospective study, patients were offered an initial
course of five single intrauterine inseminations with cryopreserved donor
spermatozoa and treatment was then reviewed. A total of 389 patients
received 1465 inseminations. In all, 1119 cycles were monitored using
luteinizing hormone serum analyses and 346 cycles using the urine home test
kits. The clinical pregnancy rate per insemination for the cycles monitored
by the serum assay was 18.0% (202/1119) compared with the urine cycles
(13.7%, 46/346) (P <05). The pregnancy loss rate was not significantly
different (14.4%, 29/202 and 21.7%, 10/46) (serum and urine cycles
respectively). The viable clinical pregnancy rate was significantly higher
(P <03) for the serum cycles than for the cycles using the urinary
monitoring (15.5%, 173/1119 and 10.4%, 36/346 respectively). The cycles
monitored by serum assay had a significantly higher cumulative viable
clinical pregnancy rate (P <0001) of 70.2% after nine inseminations
compared with the urine monitored cycles of 54.8%. The majority of patients
opted for the serum cycles, with a minority self-selecting the urine cycles
mainly for travelling convenience. The explanation for the significant
differences between the viable clinical pregnancy rates per insemination
and the cumulative viable clinical pregnancy rates may be due to the
sensitivity of the urine home test kit or the patients' interpretation of
the result.
相似文献
99.
100.
James B. Harris MD Richard C. Ahrens MD Gary Milavetz PharmD Linda Annis Rebecca Ries BA Connie Hendricker RRT 《The Journal of allergy and clinical immunology》1990,85(6):1043-1049
Inhaled beta-agonists can produce bronchodilatation and reduce airway hyperreactivity in patients with asthma. Using these two measures, we compared inhaled bitolterol (three puffs, 1110 micrograms), albuterol (two puffs, 180 micrograms), and placebo administered by metered-dose inhaler in a blinded, crossover study of 40 subjects with chronic asthma. On each study day, subjects underwent histamine challenges at 1 1/2 hours before, and 1/2, 2, 4, 6, and 8 hours after inhaling one of the three test-drug treatments. Both drugs produced significant bronchodilatation at 30 minutes through 4 hours and significant effects on airway reactivity at 30 minutes through 2 hours (p less than 0.05). Bitolterol also produced small but significant bronchodilator effects at 6 hours and effects on airway reactivity at 4 hours (p less than 0.05). Effects of bitolterol on airway reactivity diminished significantly more slowly than effects of albuterol in subjects with baseline provocative concentration causing a 20% fall in FEV1 greater than or equal to 1.0 mg/ml of histamine (half-life of biologic effect 1.37 versus 0.92 hours; p less than 0.05) but not in subjects with baseline provocative concentration causing a 20% fall in FEV1 less than or equal to 1.0 mg/ml (half-life of biologic effect of 1.01 versus 1.00 hours; p greater than 0.05). 相似文献