全文获取类型
收费全文 | 117673篇 |
免费 | 8888篇 |
国内免费 | 336篇 |
专业分类
耳鼻咽喉 | 1421篇 |
儿科学 | 3147篇 |
妇产科学 | 2944篇 |
基础医学 | 14986篇 |
口腔科学 | 2413篇 |
临床医学 | 11841篇 |
内科学 | 25358篇 |
皮肤病学 | 1248篇 |
神经病学 | 10000篇 |
特种医学 | 3865篇 |
外国民族医学 | 3篇 |
外科学 | 18728篇 |
综合类 | 1952篇 |
现状与发展 | 1篇 |
一般理论 | 118篇 |
预防医学 | 10114篇 |
眼科学 | 2932篇 |
药学 | 7663篇 |
中国医学 | 156篇 |
肿瘤学 | 8007篇 |
出版年
2023年 | 495篇 |
2022年 | 796篇 |
2021年 | 1951篇 |
2020年 | 1073篇 |
2019年 | 1877篇 |
2018年 | 2218篇 |
2017年 | 1656篇 |
2016年 | 1783篇 |
2015年 | 2100篇 |
2014年 | 3118篇 |
2013年 | 4910篇 |
2012年 | 6982篇 |
2011年 | 7364篇 |
2010年 | 4077篇 |
2009年 | 3781篇 |
2008年 | 6847篇 |
2007年 | 7576篇 |
2006年 | 7220篇 |
2005年 | 7408篇 |
2004年 | 7159篇 |
2003年 | 6771篇 |
2002年 | 6730篇 |
2001年 | 1373篇 |
2000年 | 1168篇 |
1999年 | 1302篇 |
1998年 | 1517篇 |
1997年 | 1338篇 |
1996年 | 1180篇 |
1995年 | 1156篇 |
1994年 | 999篇 |
1993年 | 890篇 |
1992年 | 993篇 |
1991年 | 984篇 |
1990年 | 885篇 |
1989年 | 867篇 |
1988年 | 783篇 |
1987年 | 826篇 |
1986年 | 791篇 |
1985年 | 827篇 |
1984年 | 977篇 |
1983年 | 989篇 |
1982年 | 1126篇 |
1981年 | 1052篇 |
1980年 | 975篇 |
1979年 | 634篇 |
1978年 | 671篇 |
1977年 | 727篇 |
1976年 | 611篇 |
1975年 | 542篇 |
1974年 | 520篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Phospho-akt expression is associated with a favorable outcome in non-small cell lung cancer. 总被引:3,自引:0,他引:3
Amit Shah William A Swain Donna Richardson John Edwards Duncan J Stewart Catherine M Richardson Daniel E B Swinson Dipika Patel J Louise Jones Kenneth J O'Byrne 《Clinical cancer research》2005,11(8):2930-2936
Akt, a Serine/Threonine protein kinase, mediates growth factor-associated cell survival. Constitutive activation of Akt (phosphorylated Akt, P-Akt) has been observed in several human cancers, including lung cancer and may be associated with poor prognosis and chemotherapy and radiotherapy resistance. The clinical relevance of P-Akt in non-small cell lung cancer (NSCLC) is not well described. In the present study, we examined 82 surgically resected snap-frozen and paraffin-embedded stage I to IIIA NSCLC samples for P-Akt and Akt by Western blotting and for P-Akt by immunohistochemistry. P-Akt protein levels above the median, measured using reproducible semiquantitative band densitometry, correlated with a favorable outcome (P = 0.007). Multivariate analysis identified P-Akt as a significant independent favorable prognostic factor (P = 0.004). Although associated with a favorable prognosis, high P-Akt levels correlated with high tumor grade (P = 0.02). Adenocarcinomas were associated with low P-Akt levels (P = 0.039). Akt was not associated with either outcome or clinicopathologic variables.Cytoplasmic (CP-Akt) and nuclear (NP-Akt) P-Akt tumor cell staining was detected in 96% and 42% of cases, respectively. Both CP-Akt and NP-Akt correlated with well-differentiated tumors (P = 0.008 and 0.017, respectively). NP-Akt also correlated with nodal metastases (P = 0.022) and squamous histology (P = 0.037).These results suggest P-Akt expression is a favorable prognostic factor in NSCLC. Immunolocalization of P-Akt, however, may be relevant as NP-Akt was associated with nodal metastases, a known poor prognostic feature in this disease. P-Akt may be a potential novel therapeutic target for the management of NSCLC. 相似文献
82.
William M Northway 《American journal of orthodontics and dentofacial orthopedics》2005,127(5):606-610
When you treat the congenital absence of mandibular second premolars by extracting the residual deciduous second molar and closing the space, you run the risk of flattening facial fullness, especially in patients with nonextraction features--diminished facial fullness, absence of crowding, and reduced tooth size. This challenge is heightened by the increased likelihood that these features will occur in patients who have agenesis. This article describes a new approach that has been shown to minimize such a loss of anchorage. The technique is called hemisection and involves buccolingual sectioning of the second deciduous molar, followed by removal of its distal half. As necessary, the mesial half is also removed, and space closure can be completed. The advantages, philosophy, and technique are discussed in detail. 相似文献
83.
The development of a surveillance system to monitor emergency food relief in New York State. 总被引:1,自引:1,他引:0 下载免费PDF全文
A representative sample of emergency food relief (EFR) programs was selected on the basis of a census of 1,488 EFR programs in New York State. The census was a two-stage telephone survey. EFR was provided in every county although there was considerable variation in the amount of EFR per county. The soup kitchen and food pantry components of EFR had to be differentiated. The surveillance system was operational one year after the census began. 相似文献
84.
T H Bourne D Jurkovic J Waterstone S Campbell W P Collins 《Ultrasound in obstetrics & gynecology》1991,1(1):53-59
Transvaginal ultrasonography with color flow mapping has been used to study changes in intrafollicular blood flow and morphology during follicular rupture and presumed ovulation in one human volunteer. Detailed monitoring started on day 11 of the menstrual cycle and the follicle began to rupture at 14.30 on day 13. This event was preceded by a defined rise and peak in the level of immunoreactive serum luteinizing hormone (LH) by 42 h and 17 h 20 min, respectively. Blood vessels were clearly visible in the inner ring of the follicle (the granulosa layer) at the time of the LH peak and part of the granulosa (probably containing the oocyte) started to detach before the follicle ruptured. The maximum value for the peak blood velocity in the inner vessels was observed 10 s after the start of follicular rupture and there was a concurrent increase in the impedance to blood flow, as reflected by the resistance index and the pulsatility index. The follicle took 14 min 29 s to empty and the corpus haemorrhagicum started to form about 1 min later. These preliminary data suggest that intrafollicular angiogenesis and changes in blood flow can be monitored by a relatively non-invasive technique. Changes in vascularity might be used to predict imminent ovulation and could possibly be identified or modified biochemically to help achieve or avoid a pregnancy. 相似文献
85.
Ramona A. Cole Anita Bansal Debra M. Moriarity William A. Haber William N. Setzer 《Journal of natural medicines》2007,61(4):414-417
The leaf essential oil of Eugenia zuchowskiae from Monteverde, Costa Rica, has been obtained by hydrodistillation and analyzed by GC–MS. The principal constituents of
E. zuchowskiae leaf oil were α-pinene (28.3%), β-caryophyllene (13.2%), α-humulene (13.1%), and α-copaene (8.1%). The leaf essential oil
of E. zuchowskiae showed pronounced in-vitro cytotoxic activity against MCF-7, MDA-MB-468, and UACC-257 human tumor cell lines. The major components
showed cytotoxic activities comparable to doxorubicin (LC50 14–70 μg/ml). 相似文献
86.
87.
88.
Minimally Invasive Coronary Artery Bypass Grafting: A New Method Using an Anterior Mediastinotomy 总被引:2,自引:0,他引:2
M. Clive Robinson M.D. David R. Gross D.V.M. Ph.D. William Zeman M.D. Eric Stedje-Larsen M.D. 《Journal of cardiac surgery》1995,10(5):529-536
The benefit of internal mammary artery (IMA) grafting as a long-lasting intervention for coronary artery disease is well recognized. However, largely because they are less invasive, catheter based alternatives are frequently chosen, particularly to treat single or double vessel disease. To retain the advantages of the IMA graft, and to offset the invasiveness of conventional coronary artery bypass grafting, we developed a new minimally invasive method using an anterior mediastinotomy for treating left anterior descending (LAD) or right coronary artery disease, or both. Feasibility studies using 16 pigs and a human cadaver led to approval by the Institutional Review Board for use of this procedure to treat six patients (four men, two women; mean age, 63.8 ± 13.6 [SD] yrs) who granted informed consent. Pedicle dissection of the IMA, using video assisted thoracoscopy if necessary, was made through a 2-to 3-inch horizontal anterior mediastinotomy. The underlying LAD artery was grafted during femoral vessel cardiopulmonary bypass, with cooling to 30°C, induced ventricular fibrillation, and left ventricular venting if required. Transesophageal echocardiography performed after bypass showed that two patients maintained normal wall motion and four had improvement from the original impairment. One patient suffered a recurrence of angina 4 weeks after the procedure; recatheterization showed an acutely angled IMA, subsequently corrected by balloon angioplasty. The results of follow-up dobutamine echocardiographic stress tests were negative in all patients. With this minimally invasive approach, the procedure should provide the benefits of IMA grafting with shorter hospital stay, more rapid recovery, and less overall cost. 相似文献
89.
G. Bradley Schaefer James N. Thompson John B. Bodensteiner James M. McConnell William J. Kimberling Charles T. Gay William D. Dutton David C. Hutchings Stanton B. Gray 《Annals of neurology》1996,39(3):382-385
There are conflicting reports on the relationship between cerebellar vermal lobule hypoplasia and autism. Using quantitative magnetic resonance image analysis, we measured the cerebellar vermis in 125 normal individuals with a broad age range and 102 patients with a variety of neurogenetic abnormalities. We conclude that hypoplasia of cerebellar vermal lobules VI and VII is a nonspecific finding that even occurs in several conditions without autistic behavior. This suggests that it is not a specific neuroanatomical marker for autism, nor is cerebellar dys- genesis likely to be solely responsible for clinical autistic behaviors. 相似文献
90.