全文获取类型
收费全文 | 36247篇 |
免费 | 2905篇 |
国内免费 | 356篇 |
专业分类
耳鼻咽喉 | 394篇 |
儿科学 | 1031篇 |
妇产科学 | 961篇 |
基础医学 | 4649篇 |
口腔科学 | 612篇 |
临床医学 | 3777篇 |
内科学 | 7744篇 |
皮肤病学 | 850篇 |
神经病学 | 2435篇 |
特种医学 | 1293篇 |
外科学 | 4913篇 |
综合类 | 1214篇 |
一般理论 | 32篇 |
预防医学 | 1986篇 |
眼科学 | 1612篇 |
药学 | 2720篇 |
中国医学 | 307篇 |
肿瘤学 | 2978篇 |
出版年
2023年 | 266篇 |
2022年 | 513篇 |
2021年 | 961篇 |
2020年 | 621篇 |
2019年 | 788篇 |
2018年 | 1016篇 |
2017年 | 769篇 |
2016年 | 889篇 |
2015年 | 1065篇 |
2014年 | 1399篇 |
2013年 | 1677篇 |
2012年 | 2360篇 |
2011年 | 2466篇 |
2010年 | 1444篇 |
2009年 | 1278篇 |
2008年 | 1926篇 |
2007年 | 2016篇 |
2006年 | 2004篇 |
2005年 | 1942篇 |
2004年 | 1707篇 |
2003年 | 1593篇 |
2002年 | 1419篇 |
2001年 | 1126篇 |
2000年 | 1055篇 |
1999年 | 909篇 |
1998年 | 395篇 |
1997年 | 304篇 |
1996年 | 282篇 |
1995年 | 230篇 |
1994年 | 209篇 |
1993年 | 215篇 |
1992年 | 456篇 |
1991年 | 445篇 |
1990年 | 425篇 |
1989年 | 412篇 |
1988年 | 361篇 |
1987年 | 376篇 |
1986年 | 333篇 |
1985年 | 286篇 |
1984年 | 210篇 |
1983年 | 158篇 |
1982年 | 99篇 |
1981年 | 98篇 |
1980年 | 96篇 |
1979年 | 142篇 |
1978年 | 93篇 |
1977年 | 80篇 |
1976年 | 85篇 |
1975年 | 79篇 |
1972年 | 69篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
OBJECTIVE: To assess changes in sociodemographic characteristics of mothers, their obstetric management and perinatal outcomes in the 1980s. DESIGN: A survey of data recorded in the South Australian perinatal data collection. For singleton births, we compared risks of stillbirth, neonatal death and perinatal death by year of birth, after adjusting for risk factors. SUBJECTS: There were 176,637 births of at least 400 g birthweight (or at least 20 weeks' gestation) notified to the perinatal data collection between 1981 and 1989. MAIN OUTCOME MEASURES: Frequency of risk factors and relative risks of stillbirth, neonatal death and perinatal death by year of birth. RESULTS: There have been changes in the sociodemographic characteristics of mothers, their obstetric management and perinatal outcomes during the 1980s. Crude perinatal mortality rates have not increased, despite increases in the frequency of low birthweight, preterm births, mothers aged 35 years and over, and some other risk factors. After adjusting for risk factors, the risks of stillbirth, neonatal death and perinatal death were lower among singletons in 1987-1989 than in the 1981-1982 reference period. CONCLUSION: Advances in clinical management may be preventing increases in stillbirths, neonatal deaths and perinatal deaths in response to increased numbers of births with low birthweight, preterm delivery and some other risk factors in South Australia. 相似文献
102.
In a group of patients with breast lumps, diagnosis made by pre-operative aspiration cytology was compared with that obtained by histological section of excised specimens. Results showed that aspiration cytology correctly diagnosed 89% of malignant lesions and 92.6% of benign lesions based upon histological diagnosis. Cytological diagnosis of benign disease had a false negative rate of 6% while cytological diagnosis of malignant disease had a 2.7% false positive rate. Only 3.5% of cytologies returned an inadequate diagnosis. This study shows that aspiration cytology should be useful in allowing a better psychological preparation of patients before surgery as well as better utilization of operation theatre facilities. 相似文献
103.
104.
Regional anaesthesia provides many advantages and can be practised safely in ambulatory surgery. It provides better postoperative pain control, avoids many complications associated with general anaesthesia and shortens recovery time. However, extra time required, associated complications and acceptance of patients are the factors of concern in practising regional anaesthesia in an ambulatory setting. This review will discuss various regional anaesthesia techniques suitable for outpatients. 相似文献
105.
R F Lai A Fat M Harboe J C Chan Pin Jin M M Diesselhoff-den Dulk R van Furth 《International journal of leprosy and other mycobacterial diseases : official organ of the International Leprosy Association》1988,56(4):552-558
For the detection of the synthesis in vitro of anti-Mycobacterium leprae antibodies in various tissues of leprosy patients, biopsy specimens of skin lesions, nasal mucosa, larynx, lymph nodes, and bone marrow were cultured in a medium containing 14C-labeled lysine and isoleucine. The culture fluids were analyzed by crossed immunoelectrophoresis with intermediate gel and autoradiography. The results show that synthesis of anti-M. leprae antibodies occurs at the investigated sites of leprosy patients and that the specificities of the synthesized antibodies differ between sites in individual patients. It is conceivable that these antibodies play a role in the local defense against M. leprae. 相似文献
106.
107.
One hundred eighty-two fine needle aspirations (FNAs) of head and neck masses performed between the years 1981 and 1987 were studied retrospectively. Seventeen FNAs were unsatisfactory. Of the remaining 165, 148 (90%) were followed up with either surgery or clinical follow-up of at least 12 months' duration. Seventy-one of these aspirates were malignant. Fifty-six cases of metastatic carcinoma and 13 cases of lymphoma were diagnosed. The positive predictive value for metastatic carcinoma and lymphoma was 100%, and the sensitivities were 92% and 100%, respectively. For benign salivary gland lesions, the positive predictive value was 94%, whereas for malignant lesions it was 100%. One case of carcinoma ex-pleomorphic adenoma was missed by FNA. No complications were associated with FNA. We conclude that FNA is a safe and accurate technique, well suited to the in-office evaluation of neck masses of differing causes. 相似文献
108.
Hidenori Endo Chikako Nito Hiroshi Kamada Tatsuro Nishi Pak H Chan 《Journal of cerebral blood flow and metabolism》2006,26(12):1479-1489
Recent studies have revealed that the phosphatidylinositol 3-kinase (PI3-K) pathway is involved in apoptotic cell death after experimental cerebral ischemia. The serine-threonine kinase, Akt, functions in the PI3-K pathway and prevents apoptosis by phosphorylation at Ser473 after a variety of cell death stimuli. After phosphorylation, activated Akt inactivates other apoptogenic factors, including glycogen synthase kinase-3beta (GSK3beta), thereby inhibiting cell death. However, the role of Akt/GSK3beta signaling in the delayed death of hippocampal neurons in the CA1 subregion after transient global cerebral ischemia (tGCI) has not been clarified. Transient global cerebral ischemia for 5 mins was induced by bilateral common carotid artery occlusion combined with hypotension. Western blot analysis showed a significant increase in phospho-Akt (Ser473) and phospho-GSK3beta (Ser9) in the hippocampal CA1 subregion after tGCI. Immunohistochemistry showed that expression of phospho-Akt (Ser473) and phospho-GSK3beta (Ser9) was markedly increased in the vulnerable CA1 subregion, but not in the ischemic-tolerant CA3 subregion. Double staining with phospho-GSK3beta (Ser9) and terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling showed different cellular distributions in the CA1 subregion 3 days after tGCI. Phosphorylation of Akt and GSK3beta was prevented by LY294002, a PI3-K inhibitor, which facilitated subsequent DNA fragmentation 3 days after tGCI. Moreover, transgenic rats that overexpress copper/zinc-superoxide dismutase, which is known to be neuroprotective against delayed hippocampal CA1 injury after tGCI, had enhanced and persistent phosphorylation of both Akt and GSK3beta after tGCI. These findings suggest that activation of the Akt/GSK3beta signaling pathway may mediate survival of vulnerable hippocampal CA1 neurons after tGCI. 相似文献
109.
110.
Multiclefted nuclei. A helpful feature for identification of intermediate trophoblastic cells in uterine curetting specimens. 总被引:1,自引:0,他引:1
Intermediate trophoblast is a distinct form of trophoblast, the presence of which in uterine curettings is considered a reliable indicator of intrauterine pregnancy even in the absence of chorionic villi. However, the appearance of intermediate trophoblastic cells have not been described in sufficiently specific terms to permit their reliable identification, and distinction from decidual cells can be difficult. We have noticed for some time that the intermediate trophoblastic cells often show multiple deep clefts in the nuclei, and the present study was performed to address the issue of whether this nuclear feature is reliable for their identification. We reviewed 242 uterine curettings of intrauterine pregnancy, documented by the presence of chorionic villi, and were able to find a distinct population of cells with large, hyperchromatic, multiclefted nuclei scattered in the decidua in 88% of the cases. In most instances, these cells produced a characteristic variegated pattern that was readily recognizable at low magnification. Positive immunostaining for cytokeratin (CAM 5.2) in these isolated cells within the decidua confirmed their trophoblastic nature. In contrast, multiclefted nuclei were absent in the 51 negative control cases, which included decidualized endocervical polyps (40 cases), uterine curettings from patients with tubal pregnancy (10 cases), and endometriosis with decidual change (one case). We conclude that intermediate trophoblastic cells can usually be reliably identified in curettings of intrauterine pregnancy by their characteristic nuclear multiclefting. 相似文献