全文获取类型
收费全文 | 3292篇 |
免费 | 349篇 |
国内免费 | 31篇 |
专业分类
耳鼻咽喉 | 17篇 |
儿科学 | 189篇 |
妇产科学 | 34篇 |
基础医学 | 461篇 |
口腔科学 | 178篇 |
临床医学 | 378篇 |
内科学 | 659篇 |
皮肤病学 | 134篇 |
神经病学 | 152篇 |
特种医学 | 203篇 |
外科学 | 548篇 |
综合类 | 68篇 |
预防医学 | 189篇 |
眼科学 | 111篇 |
药学 | 156篇 |
中国医学 | 8篇 |
肿瘤学 | 187篇 |
出版年
2023年 | 23篇 |
2022年 | 29篇 |
2021年 | 50篇 |
2020年 | 26篇 |
2019年 | 38篇 |
2018年 | 82篇 |
2017年 | 71篇 |
2016年 | 67篇 |
2015年 | 89篇 |
2014年 | 120篇 |
2013年 | 163篇 |
2012年 | 113篇 |
2011年 | 109篇 |
2010年 | 121篇 |
2009年 | 132篇 |
2008年 | 107篇 |
2007年 | 137篇 |
2006年 | 124篇 |
2005年 | 103篇 |
2004年 | 115篇 |
2003年 | 86篇 |
2002年 | 95篇 |
2001年 | 78篇 |
2000年 | 68篇 |
1999年 | 95篇 |
1998年 | 128篇 |
1997年 | 109篇 |
1996年 | 117篇 |
1995年 | 77篇 |
1994年 | 97篇 |
1993年 | 58篇 |
1992年 | 83篇 |
1991年 | 76篇 |
1990年 | 55篇 |
1989年 | 81篇 |
1988年 | 59篇 |
1987年 | 68篇 |
1986年 | 66篇 |
1985年 | 61篇 |
1984年 | 39篇 |
1983年 | 27篇 |
1982年 | 28篇 |
1981年 | 23篇 |
1980年 | 24篇 |
1979年 | 27篇 |
1978年 | 11篇 |
1977年 | 24篇 |
1976年 | 17篇 |
1975年 | 13篇 |
1973年 | 10篇 |
排序方式: 共有3672条查询结果,搜索用时 15 毫秒
51.
52.
We have cloned four cyclin-B homologs from Saccharomyces cerevisiae, CLB1-CLB4, using the polymerase chain reaction and low stringency hybridization approaches. These genes form two classes based on sequence relatedness: CLB1 and CLB2 show highest homology to the Schizosaccharomyces pombe cyclin-B homolog cdc13 involved in the initiation of mitosis, whereas CLB3 and CLB4 are more highly related to the S. pombe cyclin-B homolog cig1, which appears to play a role in G1 or S phase. CLB1 and CLB2 mRNA levels peak late in the cell cycle, whereas CLB3 and CLB4 are expressed earlier in the cell cycle but peak later than the G1-specific cyclin, CLN1. Analysis of null mutations suggested that the CLB genes exhibit some degree of redundancy, but clb1,2 and clb2,3 cells were inviable. Using clb1,2,3,4 cells rescued by conditional overproduction of CLB1, we showed that the CLB genes perform an essential role at the G2/M-phase transition, and also a role in S phase. CLB genes also appear to share a role in the assembly and maintenance of the mitotic spindle. Taken together, these analyses suggest that CLB1 and CLB2 are crucial for mitotic induction, whereas CLB3 and CLB4 might participate additionally in DNA replication and spindle assembly. 相似文献
53.
Functional consequences of ROMK mutants linked to antenatal Bartter's syndrome and implications for treatment 总被引:4,自引:0,他引:4
The antenatal variant of Bartter's syndrome is an autosomal recessive
kidney disease characterized by polyhydramnios, premature delivery,
hypokalemic alkalosis and hypercalciuria. It is genetically heterogeneous,
having been linked recently to mutations in an ATP- sensitive, renal outer
medullary K+channel, ROMK, and earlier to mutations in the Na-K-2Cl
co-transporter, NKCC2. We characterized four of the mutations reported in
three heterozygous ROMK variants of antenatal Bartter's and found that each
expressed a distinct phenotype in Sf9 cells. One mutation expressed normal
function and appears to be an allelic polymorphism. The other three
mutations produced channels with significantly reduced K+fluxes. However,
the mechanisms in each case were different and reflected abnormalities in
phosphorylation, proteolytic processing or protein trafficking. The
different mechanisms may be important in the design of appropriate therapy
for patients with this disease.
相似文献
54.
Uterine myomata and outcome of assisted reproduction 总被引:5,自引:8,他引:5
Ramzy AM; Sattar M; Amin Y; Mansour RT; Serour GI; Aboulghar MA 《Human reproduction (Oxford, England)》1998,13(1):198-202
The aim of this work was to study the effect of uterine myomata on the
implantation rate and outcome in in-vitro fertilization (IVF) and
intracytoplasmic sperm injection (ICSI). Among 406 patients, 51 (12.6%)
were found to have uterine corporeal myomata. Twelve patients were excluded
from the study as they had large myomata, submucous myomata or intramural
myomata encroaching on the cavity. These patients were advised to have
myomectomy before being enrolled in the IVF/ICSI programme. The remaining
patients (n = 39) were sorted according to the number, site and size of the
myomata as assessed by transvaginal sonography. Three patients had more
than one myoma. Most of the myomata were subserous (72.7%) and the mean
diameter of the myomata was 3.5 +/- 0.9 cm. A control group (n = 367) was
chosen with normal uteri and no history of uterine reconstruction surgery.
The mean age of myoma patients was 34.7 +/- 3.6 years as compared to 34.0
+/- 4.4 years in the control group. The age, period of infertility, body
mass index, duration and number of human menopausal gonadotrophin ampoules
needed for stimulation, oestradiol levels, number of oocytes retrieved and
the fertilization rate were not significantly different in the myoma
patients compared to the control group. Fifteen myoma patients (38.5%)
subsequently showed one or more pregnancy sacs on ultrasonography of which
three (20%) spontaneously aborted during the first trimester and two
(13.3%) had preterm labour, as compared to 123 (33.5%), 19 (15.5%) and nine
(7.3%) respectively, among the control group (P = 0.27, 0.33 and 0.21). In
conclusion, uterine corporeal myomata, not encroaching on the cavity and
<7 cm in mean diameter, do not affect the implantation or miscarriage
rates in IVF or ICSI.
相似文献
55.
56.
Germline mutations of the CDKN2 gene in UK melanoma families 总被引:4,自引:1,他引:4
Harland M; Meloni R; Gruis N; Pinney E; Brookes S; Spurr NK; Frischauf AM; Bataille V; Peters G; Cuzick J; Selby P; Bishop DT; Bishop JN 《Human molecular genetics》1997,6(12):2061-2067
Germline mutations in CDKN2 on chromosome 9p21, which codes for the cyclin
D kinase inhibitor p16, and more rarely, mutations in the gene coding for
CDK4, the protein to which p16 binds, underlie susceptibility in some
melanoma families. We have sequenced all exons of CDKN2 and analysed the
CDK4 gene for mutations in 27 UK families showing evidence of
predisposition to melanoma. Five different germline mutations in CDKN2 were
found in six families. Three of the mutations (Met53Ile, Arg24Pro and
23ins24) have been reported previously. We have identified two novel CDKN2
mutations (88delG and Ala118Thr) which are likely to be associated with the
development of melanoma, because of their co-segregation with the disease
and their likely functional effect on the CDKN2 protein. In binding assays
the protein expressed from the previously described mutation, Met53Ile, did
not bind to CDK4/CDK6, confirming its role as a causal mutation in the
development of melanoma. Ala118Thr appeared to be functional in this assay.
Arg24Pro appeared to bind to CDK6, but not to CDK4. No mutations were
detected in exon 2 of CDK4, suggesting that causal mutations in this gene
are uncommon. The penetrance of these mutant CDKN2 genes is not yet
established, nor is the risk of non-melanoma cancer to gene carriers.
相似文献
57.
Determination of the parent of origin in nine cases of prenatally detected chromosome aberrations found after intracytoplasmic sperm injection 总被引:1,自引:17,他引:1
Van Opstal D; Los FJ; Ramlakhan S; Van Hemel JO; Van Den Ouweland AM; Brandenburg H; Pieters MH; Verhoeff A; Vermeer MC; Dhont M; In't Veld PA 《Human reproduction (Oxford, England)》1997,12(4):682-686
Prenatal cytogenetic analysis of 71 fetuses conceived by intracytoplasmic
sperm injection (ICSI) resulted in the detection of nine (12.7%) chromosome
aberrations including two cases of 47,XXY, four cases involving a 45,X cell
line and three autosomal trisomies. Molecular analysis of the parental
origin of the deleted or supernumerary chromosome was performed by using
polymorphic microsatellite markers. Six cases involving a sex chromosome
abnormality were found to be of paternal origin while the two trisomic
cases that could be analysed were of maternal origin. Two cases involved
the same infertile couple who had two consecutive ICSI pregnancies
terminated because of a chromosome abnormality. The replaced embryos in
both cases originated from a single batch of ICSI fertilized oocytes of
which part was used to initiate the first pregnancy and part was
cryopreserved and used to initiate the second pregnancy.
相似文献
58.
59.
60.