全文获取类型
收费全文 | 11927篇 |
免费 | 930篇 |
国内免费 | 101篇 |
专业分类
耳鼻咽喉 | 90篇 |
儿科学 | 372篇 |
妇产科学 | 275篇 |
基础医学 | 1319篇 |
口腔科学 | 193篇 |
临床医学 | 1165篇 |
内科学 | 2551篇 |
皮肤病学 | 187篇 |
神经病学 | 832篇 |
特种医学 | 494篇 |
外科学 | 1842篇 |
综合类 | 267篇 |
一般理论 | 7篇 |
预防医学 | 709篇 |
眼科学 | 979篇 |
药学 | 747篇 |
中国医学 | 70篇 |
肿瘤学 | 859篇 |
出版年
2023年 | 112篇 |
2022年 | 141篇 |
2021年 | 300篇 |
2020年 | 189篇 |
2019年 | 276篇 |
2018年 | 320篇 |
2017年 | 223篇 |
2016年 | 228篇 |
2015年 | 269篇 |
2014年 | 351篇 |
2013年 | 429篇 |
2012年 | 633篇 |
2011年 | 700篇 |
2010年 | 431篇 |
2009年 | 411篇 |
2008年 | 619篇 |
2007年 | 712篇 |
2006年 | 690篇 |
2005年 | 664篇 |
2004年 | 601篇 |
2003年 | 553篇 |
2002年 | 504篇 |
2001年 | 449篇 |
2000年 | 398篇 |
1999年 | 332篇 |
1998年 | 146篇 |
1997年 | 122篇 |
1996年 | 120篇 |
1995年 | 91篇 |
1994年 | 88篇 |
1993年 | 92篇 |
1992年 | 183篇 |
1991年 | 179篇 |
1990年 | 156篇 |
1989年 | 132篇 |
1988年 | 137篇 |
1987年 | 160篇 |
1986年 | 112篇 |
1985年 | 103篇 |
1984年 | 66篇 |
1983年 | 77篇 |
1982年 | 50篇 |
1981年 | 50篇 |
1980年 | 47篇 |
1979年 | 68篇 |
1978年 | 50篇 |
1977年 | 23篇 |
1976年 | 17篇 |
1973年 | 17篇 |
1972年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Tang NL Hui J Law LK Lam YY Chan KY Yeung WL Chan AY Cheung KL Fok TF 《Human mutation》2000,16(5):446
Glutaric acidemia type I is caused by mutations of the glutaryl-CoA dehydrogenase (GCDH) gene resulting in loss of GCDH enzyme activity. Patients present with progressive dystonia and lesions in basal ganglia. Dietary treatment, when instituted from the early neonatal period, markedly reduces dystonia and morbidity. Early diagnosis and prenatal diagnosis will be facilitated by knowledge of locally prevalent GCDH mutations. Several common GCDH mutations have been found in different ethnic groups. GCDH mutations were studied in 5 Chinese glutaric acidemia type I families. We detected two novel recurrent mutations (A219T and IVS10-2A>C) which were found in two unrelated families. An asymptomatic carrier of IVS10-2A>C was also found on screening of 120 individuals. Other mutations were identified, including two other novel (R386G & IVS3+1G>A) and two known mutations (G178R & R355H). Fibroblasts from patients carrying the novel mutations were confirmed to be deficient for GCDH activity. This is the first report of GCDH mutations describing recurrent mutations in Chinese patients. The carrier rate of IVS10-2A>C may be particularly high in Chinese. 相似文献
92.
Induction of a differentiated ciliated cell phenotype in primary cultures of Fallopian tube epithelium 总被引:5,自引:1,他引:5
Human Fallopian tubal epithelial cells in culture lose morphological
features associated with the epithelium in situ and the extent to which
they retain their in-vivo phenotype or function is unknown. In order to
address this question, immunocytochemical markers were identified which
distinguish secretory (HMFG2+, LhS28-) from ciliated (HMFG2-, LhS28+)
epithelial cells in tissue sections of Fallopian tube. These markers were
used to analyse the phenotype of tubal cells in vitro. Primary cultures of
human tubal epithelial cells were seeded onto glass and grown to confluence
before addition of oestradiol-17beta. In the absence of hormone, tubal
epithelial cells expressed cytokeratins and nuclear receptors for oestrogen
and progesterone and adopted a homogeneous (HMFG2+, LhS28-) secretory cell
phenotype. Following the addition of oestradiol-17beta, a proportion of
cells became positive for LhS28. The induction of a ciliated epithelial
cell phenotype was confirmed by scanning electron microscopy, where on
permeable collagen membranes, approximately one-third of tubal epithelial
cells became ciliated in the presence of oestradiol-17beta. We suggest that
in vitro, tubal epithelial cells adopt an immature secretory-like phenotype
and that oestrogen can induce differentiation to a ciliated epithelial cell
phenotype.
相似文献
93.
Chloe Miu Mak Ching-Wan Lam Sidney Tam Ching-Lung Lai Lik-Yuen Chan Sheung-Tat Fan Yu-Lung Lau Sik-To Lai Patrick Yuen Joannie Hui Chun-Cheung Fu Ka-Sing Wong Wing-Lai Mak Kong Tze Sui-Fan Tong Abby Lau Nancy Leung Aric Hui Ka-Ming Cheung Chun-Hung Ko Yiu-Ki Chan Oliver Ma Tai-Nin Chau Alexander Chiu Yan-Wo Chan 《Journal of human genetics》2008,53(4):375-375
94.
Histone deposition protein Asf1 maintains DNA replisome integrity and interacts with replication factor C 总被引:9,自引:0,他引:9 下载免费PDF全文
Chromatin assembly and DNA replication are temporally coupled, and DNA replication in the absence of histone synthesis causes inviability. Here we demonstrate that chromatin assembly factor Asf1 also affects DNA replication. In budding yeast cells lacking Asf1, the amounts of several DNA replication proteins, including replication factor C (RFC), proliferating cell nuclear antigen (PCNA), and DNA polymerase epsilon (Pol epsilon), are reduced at stalled replication forks. In contrast, DNA polymerase alpha (Pol alpha) accumulates to higher than normal levels at stalled forks in asf1Delta cells. Using purified, recombinant proteins, we demonstrate that RFC directly binds Asf1 and can recruit Asf1 to DNA molecules in vitro. We conclude that histone chaperone protein Asf1 maintains a subset of replication elongation factors at stalled replication forks and directly interacts with the replication machinery. 相似文献
95.
AIMS: To investigate the serum creatine kinase isoenzyme pattern, specific biochemical markers of bone metabolism, and cytokines in a Chinese family with osteopetrosis, and correlate abnormalities with the pathophysiology of this condition. METHODS: A Chinese female baby was diagnosed with malignant infantile osteopetrosis at the age of 3 weeks by clinical history and biochemical investigations. We studied the laboratory and radiological manifestations of this index case and her family members. RESULTS: Serum CK-BB fraction of our index patient was elevated to 18.0% (normal 1.6-7.6%). Her biochemical markers of bone resorption including serum C-terminal telopeptide concentration and urine N-terminal telopeptide to creatinine ratio were decreased to 0.54 microg/L (normal 0.72-1.56 microg/L) and 159 x 10(-6) (normal 372-900 x 10(-6)), respectively. Serum cytokines including soluble receptor activator of nuclear factor kappa-B ligand (sRANKL) concentration was suppressed to 0.11 pmol/L (normal 0.23-0.82 pmol/L) and osteoprotegerin (OPG) concentration was 4.9 pmol/L (normal 2.8-4.9 pmol/L), resulting in an elevated OPG to sRANKL ratio of 44.5 (normal 3.8-19.4) in favour of bone formation. CONCLUSIONS: If left untreated, this condition is usually fatal within the first year of life. With early diagnosis, management including bone marrow transplantation can be planned ahead and will result in a better survival. 相似文献
96.
Identification of enterovirus 71 isolates from an outbreak of hand, foot and mouth disease (HFMD) with fatal cases of encephalomyelitis in Malaysia 总被引:11,自引:0,他引:11
Thirteen enterovirus 71 (EV71) isolates were obtained from both fatal and non-fatal infections of patients seen in Peninsula Malaysia and in Sarawak during an outbreak of hand, foot and mouth disease (HFMD) in Malaysia in 1997, with incidences of fatal brainstem encephalomyelitis. The isolates were identified using immunofluorescence staining, neutralization assays, and partial sequencing of the 5' untranslated regions (UTR). Assessment of the potential genetic relationships of the isolates using the partial 5'UTR sequences suggested clustering of the isolates into at least two main clusters. Isolates from Peninsula Malaysia were found in both clusters whereas Sarawak-derived isolates clustered only in cluster II. Isolates derived from fatal infections, however, occurred in both clusters and no distinctive nucleotide sequences could be attributed to the fatal isolates. Examination of the nucleotide sequences revealed at least 13 nucleotide positions in all the isolates which differ completely from the previously reported EV71 5'UTR sequences. In addition, at least 11 nucleotide position differences within the 5'UTR were noted which differentiated cluster I from cluster II. Predicted secondary RNA structures drawn using the nucleotide sequences also suggested differences between isolates from the two clusters. These findings suggest the presence of at least two potentially virulent EV71 co-circulating in Malaysia during the 1997 HFMD outbreak. 相似文献
97.
Myotonic dystrophy (DM) is a multisystemic disorder caused by an inherited CTG repeat expansion which affects three genes encoding the DM protein kinase (DMPK), a homeobox protein Six5 and a protein containing WD repeats. Using a panel of 16 monoclonal antibodies against several different DMPK epitopes we detected DMPK, as a single protein of approximately 80 kDa, only in skeletal muscle, cardiac muscle and, to a lesser extent, smooth muscle. Many earlier reports of DMPK with different sizes and tissue distributions appear to be due to antibody cross-reactions with more abundant proteins. One such antibody, MANDM1, was used to isolate two related protein kinases, MRCK alpha and beta, from a human brain cDNA library and the shared epitope was located at the catalytic site of DMPK using a phage-displayed random peptide library. The peptide library also identified an epitope shared between DMPK and a 55 kDa muscle-specific protein. The results suggest that effects of the repeat expansion on the DMPK gene may be responsible for muscle and heart features of DM, whereas clinical changes in other tissues may be due to effects on the other two genes. 相似文献
98.
Changes in the magnetic resonance (MR) parameters of demyelinated neural tissue were measured in vitro using an experimental animal model. A tellurium (Te) diet was applied to weanling rats to induce the demyelination process in the sciatic nerve. The quantitative MR parameters, such as T(1), T(2) relaxation time constants and magnetization transfer (MT) were measured each day after applying the Te diet (up to 7 days) and were found to be substantially different from those of normal nerves. An increase in the average T(1) and T(2) was observed along with a decrease in the MT ratio (MTR) and the quantitative MT parameter M(0B), which describes the semisolid pool of protons. Most of the MR parameters correlated very well with the myelin fraction of neural tissue evaluated by quantitative histopathology. The T(2) relaxation spectrum provided the most efficient quantitative assessment of changes in neural tissue microstructure and its analysis resulted in a powerful tool to distinguish the processes of demyelination and inflammation. In comparison, the MT measurements were less successful. 相似文献
99.
Collision tumour of the oesophagus: a challenge for histological diagnosis. 总被引:2,自引:0,他引:2 下载免费PDF全文
An unusual case of mantle cell lymphoma metastasising to squamous cell carcinoma of the oesophagus, in a 62 year old Chinese man, is reported. A histological diagnosis based on examination of a small endoscopic biopsy specimen, in the absence of detailed clinical information, may be difficult, as the lymphoma component can be mistaken for reactive lymphoid infiltrate which is sometimes present adjacent to squamous cell carcinoma. Correlation with the clinical history, careful assessment of the subtle histological changes, and use of ancillary methods such as immunohistochemistry are most helpful in making the correct diagnosis. This case also illustrates further the possible occurrence of lymphomatous infiltrates surrounding other lesions in patients with a previous or concurrent history of lymphoma. 相似文献
100.
Robert T. Mathie Peter H. M. Lam A. Murray Harper Leslie H. Blumgart 《Pflügers Archiv : European journal of physiology》1980,386(1):77-83
The acute effect of portal vein occlusion on hepatic arterial blood flow was studied in a group of nine anaesthetised dogs. The influence of hepatic artery denervation and total liver denervation on the hepatic arterial flow response was determined subsequently. Blood flows in the hepatic artery and portal vein were measured with electromagnetic flowmeters, and hepatic tissue perfusion with85Krypton clearance. A side-to-side mesocaval shunt was constructed to provide a drainage channel for the mesenteric venous blood during the periods of portal vein occlusion.Occlusion of the portal vein produced an immediate and significant increase in hepatic arterial flow which was sustained at approximately 80% above control for the 6 min period of observation. Total liver blood flow and hepatic tissue perfusion were both significantly reduced by about 40%. Denervation either of the hepatic artery alone or the entire liver produced no change in the response, and it is concluded that there is no neurogenic component either initiating or modifying the early changes in hepatic arterial flow. 相似文献